ABC of Occupational & Environmental Medicine, DAVID SNASHALL, second edition

ABC of Occupational and Environmental Medicine emotional experience of stress—for example, by drinking Some possible self reported symptoms of work stress more. However, this type of coping can easily become a • Anxiety about work, continually agitated secondary source of stress and ill health if sustained. • Continual complaints of unreasonable or unrelenting work Evidence shows that cognitive stress is associated with poor demands decision making, impaired concentration, reduced attention span, impaired memory, and confusion. People who report • Deep exhaustion “being stressed” also tend to admit to “not being able to think • Disturbed sleep and daytime tiredness straight.” Social behaviour and interpersonal relations may also • Expressed dislike of work or work colleagues and low job be affected, possibly reflecting these and other psychological changes such as exhaustion and increased irritability. satisfaction The effects of stress are thought to contribute to a range • Feelings of being out of control or helpless of disorders as wide as cancer, heart disease, musculoskeletal • Feelings of lack of support and care from others conditions, skin disease, gastrointestinal disorders, and sexual • Forgetfulness problems. The evidence is strongest for links between certain • Inability to concentrate, continually distracted types of prolonged stress and ischaemic heart disease, • Inability to think straight hypertension, and mental illness. Evidence also suggests that • Irritability, being short tempered stress plays a part in the aetiology, course, and outcome • Loss of sexual interest, or impaired sexual performance (recovery from disability) of musculoskeletal disorders. Most • Loss of the “big picture:” unable to get events into perspective of the evidence for such links is epidemiological. The • Repeated absences from work pathophysiological mechanisms are not clear—perhaps the effects are direct (chemical mediators, effects on immunity) or Psychosocial and organisational hazards: a taxonomy indirect (the results of secondary, damaging behaviour). Content of work It is likely that what is bad for the individual employee is also bad for their organisation. Organisational concerns • Task content: lack of variety or short work cycles, fragmented or associated with work related stress include high absenteeism, increased staff turnover, low job satisfaction, low morale, poor meaningless work, underuse of skills, high uncertainty organisational commitment, poor performance and productivity, possible increased accident and near miss rates, • Workload and workpace: work overload or underload, lack of and, in some cases, an increase in employee and client complaints and litigation. control over pacing, time pressure Causes of stress at work • Work schedule: shift working, inflexible work schedules, “Psychosocial and organisational” hazards refer to those aspects unpredictable, long or unsociable hours of the design and management of work and of its social and organisational contexts that are known to contribute to • Control: low participation in decision making, lack of control employee stress—so, to a lesser extent, do “physical” hazards such as noise and extremes of temperature. There is over work a reasonable consensus on the nature of the psychosocial and organisational hazards, and they have been divided into Context to work nine broad categories. • Organisational culture and function: poor communication, low Managing stress at work levels of support for problem solving and personal development, Work stress can be managed from two different perspectives: lack of definition of organisational objectives the individual and the organisational. The occupational health practitioner has a role to play in each approach. • Role in organisation: role ambiguity and role conflict, Education, treatment, and rehabilitation: the individual responsibility for people Much of little value has been written about individual stress management, and many weird and wonderful treatments are • Career development: career stagnation and uncertainty, under offered commercially. A healthy scepticism is warranted here as few of these treatments are based in scientific knowledge and or over promotion, poor pay, job insecurity, low social value even fewer have been evaluated. to work Three strategies that might help the individual • Interpersonal relations at work: social or physical isolation, experiencing stress through work are: further education and training in relevant work or life skills, short term treatment poor relations with superiors, interpersonal conflict, and lack for any medical condition, and managed rehabilitation to of social support a normal pattern of working life. • Home-work interface: conflicting demands of work and home, Without doubt, the most effective form of stress management training is through a proper analysis of training poor support at home, dual career problems needs in relation to the person’s job; lifestyle counselling can also be valuable. Fundamental problems in the demands-ability Adapted from Cox (1993) balance may need to be examined. At the same time, reducing health risk behaviour and strengthening health positive Work related factors and ill health: the Whitehall II Study This research concentrated on how the design of work affected people’s mental well being and related health outcomes. The key findings were as follows: • Having little say in how the work is done is associated with poor mental health in men and a higher risk of alcohol dependence in women • Work requiring a fast pace and the need to resolve conflicting priorities is associated with a higher risk of psychiatric disorder in both sexes, and poor physical fitness or illness in men • A combination of putting high effort into work and poor recognition of employees’ effort by managers is associated with increased risk of alcohol dependence in men, poor mental health in both sexes, and poor physical fitness or illness in women • A lack of understanding and support from managers and colleagues at work is associated with higher risk of psychiatric disorder. Good social support at work, particularly from managers for their staff, has a protective effect • Aspects of poor work design is also associated with employees taking more sickness absence 42

Work related stress Causes of stress and possible solutions Too many demands Lack of control Poor management culture Demands are at the right level when: People feel in control when: Examples of good management are when: • Staff are able to cope with the volume • They are given a say in how they do their • An organisation is committed to and complexity of the work work promoting the wellbeing of employees through good management practice • The work is scheduled sensibly so that • The amount of control they have is • The people who work in the organisation there is enough time to do allocated balanced against the demands placed on them are valued and respected tasks; shift work systems are agreed with Lack of training and support, and failure to • They receive support from the employees or their representatives; take account of individual factors organisation if they wish to raise people are not expected to work long problems affecting their work Examples of good practice: hours over an extended period Poor relations • Employees receive suitable and sufficient Examples of good relations are when: Poor management of change training to do their jobs • There is good communication between Good change management includes when the • Employees receive support from their employer and employees, so that the organisation: employees understand what is expected, immediate line management, even when and the employer reacts to any problems • Communicates to employees the reason things go wrong experienced by the employees why change is essential • The organisation encourages people to • Employees are not bullied or harassed, • Has a clear understanding of what it share their concerns about health and and policies are in place to manage this safety and, in particular, work related wants change to achieve stress Role uncertainty People understand their role when: • Has a timetable for implementing • The individual is fair to the employer— • They know why they are undertaking the change, which includes realistic first steps they discuss their concerns and work towards agreed solutions work and how this fits in with the • Ensures a supportive climate for organisation’s wider aims and objectives employees • Jobs are clearly defined to avoid confusion behaviour such as exercise and relaxation may both improve Expectations of a person experiencing stress through work the person’s psychological and physical health, and offer a distraction from their problems. • Timely and appropriate support from both management and If the person is affected by anxiety, depression, or some occupational health other stress induced illness, then that should be treated in the conventional way, possibly with drugs or psychological • A professional and sensitive approach treatments, but always appropriately combined with education • Help in solving the problem at source: moderating work and rehabilitation. Managed rehabilitation is critical to the success of any treatment for work stress, and necessarily entails pressures, providing education and training, increasing control a dialogue between the occupational health practitioner and over work events, and improving support line management. • Advice, if necessary, on lifestyle Prevention and an appropriate response: the organisation • Short term treatment for any associated medical problems Employers have a duty of care under common law to take • Active management of rehabilitation to work reasonable and practicable steps to protect their employees’ safety and health at work. This duty clearly extends to psychological as well as physical health, and to psychosocial and organisational as well as physical hazards. It is clear that an employer’s failure to consider stress seriously can result in legal challenge. Employers also have duties under statutory health and safety law. Such law has evolved to prevent harm to employees through work, whereas common law allows for financial redress when harm has occurred. These two bodies of law are complementary, as are the duties they impose. The occupational health practitioner can advise employers on two issues: prevention through risk management, and provision of employee support systems. According to guidance from the Health and Safety Executive in the United Kingdom and the European Commission, work stress is to be treated as a health and safety issue and dealt with in organisations through the application of a risk management approach (essentially systematic problem solving). Organisations will need to include methods of assessing the risk from exposure to psychosocial and organisational hazards in their routine assessments and develop ways of reducing such risks if necessary. Methods to do this are 43

ABC of Occupational and Environmental Medicine available, and occupational health practitioners have a major The box containing information on psychosocial and organisational role to play both as expert advisers and organisational hazards is adapted from Cox 1993. The box containing causes of stress champions. and possible solutions is adapted from Health and Safety Executive. Work related factors and ill health: the Whitehall II study. Sudbury: HSE Books, The successful provision of employee support (to deal with 2000 (CRR 266/2000). stress) depends on three things: a broad based and competent system, an accessible system, and an integrated system. Most large organisations provide good employee support in theory, but fail themselves and their employees in practice because the overall system is fragmented, often competitive for resources, and territorial, and lacks internal collaboration at the case level. Much can be achieved by bringing existing systems together, by training staff in relation to work stress, and by marketing what is available within the organisation. Further reading • Cox T, Griffiths A, Randall R. A risk management approach • Cox T, Griffiths A, Rial-Gonzalez E. Work-related stress. to the prevention of work stress. In: Schabracq MA, Winnubst JAM, Cooper C, eds. Handbook of work and health psychology, Luxembourg: Office for Official Publications of the European 2nd ed. Chichester: Wiley and Sons, 2002. A detailed discussion Communities, 2000. A compact overview of the professional and scientific literature on work stress; incorporates a discussion of the risk of the risk management approach to work stress; includes a short management approach to dealing with stress problems at work. Can be downloaded free from the website of the European Agency for Safety and series of organisational case studies to illustrate that approach in Health at Work: http://osha.eu.int practice. The chapter touches on risk reduction strategies that focus • Cox T. From environmental exposure to ill health. In: McCaig R, on the individual employee as well as those that operate at the Harrington M, eds. The changing nature of occupational health. Sudbury: HSE Books, 1998. This chapter in an edited volume organisational level in memory of Dr Thomas Legge provides a more detailed account of the model of stress referred to here, with more information from the • Griffiths A, Randall R, Santos A, Cox T. Senior nurses: organisational perspective. It also includes further discussion of the individual perspective interventions to reduce work stress. In: Dollard M, Winefield A, eds. Occupational stress in service professionals. London: Taylor and • Griffiths A. The psychosocial work environment. In: McCaig R, Francis, 2002. Provides a relatively detailed case study of Harrington M, eds. The changing nature of occupational health. an organisational intervention to manage work stress in a group of Sudbury: HSE Books, 1998. This chapter, in what has become known as the Thomas Legge book, focuses on the psychosocial work environment hospital based senior nurses applying the risk management approach. and provides an informed and detailed discussion of the psychosocial and organisational aspects of work, their design, and management. This As with the above chapter, there is some discussion of risk reduction chapter is usefully read in conjunction with that by the author in the same volume strategies that focus on the individual employee • Health and Safety Executive. The scale of occupational stress: the Bristol stress and health at work study. Sudbury: HSE Books, 2000 (CRR 265/2000) • Health and Safety Executive. Work related factors and ill health: the Whitehall II study—CRR 266/2000, Sudbury: HSE Books, 2000 44

9 Mental health at work Rachel Jenkins Introduction The spectrum of mental health disorders Mental illness affects about a tenth of all adults at any one Disorder Rough prevalence time—about 450 million people worldwide. Lifetime prevalence Psychological distress usually Most of us from time to time is much higher. Mental disorders now account for about 12% connected with various life of the global burden of disease and this is expected to rise to situations, events, and 10-20% of adults in general 15% by the year 2020. Neuropsychiatric conditions account for problems population but 40-50% in 30% of all years lived with disability. Common mental disorders highly vulnerable populations; (depression, anxiety disorders in 30% of primary care attenders; Mental disorders and substance abuse are important issues adults, and emotional and 10% of children in general in the workplace, partly because they are so common in the conduct disorders in children) population general adult population and partly because increasing rates of 0.5% of general population employment in many countries mean that the less able are Severe mental disorders with entering the workforce. Mental ill health at work seems to be disturbances in perception, Highly country specific; rising and in the United Kingdom at least, it has overtaken beliefs, and thought 5% and above, increasing musculoskeletal disorders as the main cause of absence from processes (psychoses) work, long term sickness, and retirement on medical grounds. Substance abuse disorders 1-5%; mostly women Whatever the cause of mental disorders, they have consequences (excess consumption and Not known; existing studies for work performance and economic productivity. Appropriately dependency on alcohol, suggest 5% tailored work is generally beneficial for people suffering mental drugs, and tobacco) illness, and the workplace can be an important setting for Eating disorders Senile dementia: 5% of over mental health promotion and the prevention of illness. Abnormal personality traits 65s and 20% of over 80s that are handicapping to the (hence the demographic Positive mental health is not just the absence of mental individual and/or others time bomb) disorder but has been defined as a positive sense of wellbeing, Progressive organic diseases of Situation specific implying the presence of self esteem; optimism; a sense of the brain (dementia) A growing problem in mastery and coherence; the ability to initiate, develop, and countries where people with sustain mutually satisfying personal relationships; and the ability Tropical organic dementias AIDS live long enough to to cope with adversity (resilience). Factors such as these enhance AIDS dementia develop it a person’s capacity to contribute to family and other social Industry specific (mercury, networks, the local community, and society at large. They are also Toxic organic brain syndromes lead, carbon monoxide) or qualities that may be expected to influence work performance. environmental The spectrum of mental health problems Mental disorder is common in the adult population of the Prevalence of psychiatric disorders per 1000 population in United Kingdom, as elsewhere in Europe and the rest of the world. adults aged 16-64 years in Great Britain 2000 Those who are unemployed have higher rates of mental Women Men All adults illness than people in employment, partly because of the socially stressful aspects of unemployment and partly because Rate per thousand in past week (se) people with mental illness experience more difficulty in finding and maintaining work. Rates of mental illness in employed and unemployed, Great Mixed anxiety and 112 (6) 72 (5) 92 (4) Britain 2000 depressive disorders Generalised anxiety Working Working disorder 48 (3) 46 (4) 47 (3) full time part time Unemployed Inactive Depressive episode Phobias 30 (3) 26 (3) 28 (2) Rate per thousand (se) Obsessive-compulsive 24 (2) 15 (2) 19 (2) disorder 15 (2) 10 (2) 12 (1) Neurosis (per thousand 136 (7) 161 (11) 196 (30) 270 (12) Panic disorder in past week) 6 (2) – 17 (3) Any neurotic disorder 7 (1) 8 (2) 7 (1) 202 (8) 144 (7) 173 (6) Probable psychosis (per 1 (1) Probable psychosis thousand in past year) Drug dependence Alcohol dependence 94 (5) 53 (8) 146 (25) 67 (7) Alcohol dependence Rate per thousand in past year (se) (per thousand in past 5 (1) 6 (1) 6 (1) 6 months) 24 (3) 60 (5) 42 (3) Drug dependence (per 40 (4) 32 (6) 137 (23) 40 (6) thousand in past year) Rate per thousand in past 6 months (se) Source: ONS survey of psychiatric morbidity among adults living in private 32 (3) 130 (6) 81 (4) households, 2000 45

ABC of Occupational and Environmental Medicine The prevalence of mental disorders in the workplace Study Number Population Instrument Male Female Total prevalence Fraser R, 1947 studied Light and medium engineering workers Medical 283 360 per 1000 assessment 300 3000 Middlesex 334 questionniare 452 378 Heron and 184 Colliery workers: 522 Braithwaite, 162 Sedentary Clinical interview 1953 Surface manual schedule Underground workers Jenkins R, et al., 1982 Times journalists: 1 month after redundancy notice and 2 months MacBride R, 274 before closure date General health 378 et al., 1981 3 months after redundancy notice, when questionnaire redundancy revoked and new owner arrived 324 12 weeks after threat of redundancy removed General health questionnaire 480 Air traffic controllers 270 Jenkins R, 1985 184 during an industrial dispute Clinical interview 362 343 310 4 months later schedule 10 months later 353 270 General health 310 310 Executive officers in civil service questionnaire 252 370 McGrath A, 171 Nurses General health et al., 1989 10 314 Teachers questionnaire Social workers Stansfeld S, et al., 1994 Whitehall civil servants: Admin grades 1-7 Senior executive officer, 248 Higher executive officer, 247 Clerical 216 Causes and consequences of Risk factors associated with common mental disorders: odds mental disorder ratio (OR) of sociodemographic correlates of revised clinical interview schedule (CIS-R) score of 12 or more; Causes *p Ͻ 0.05 **p Ͻ 0.01 The causation of mental disorder is multifactorial, being half genetic and half environmental for psychoses but largely Sex Adjusted 95% confidence environmental for the non-psychotic disorders. Male odds ratio interval Female Some disorders have a genetic basis, especially the major 1.00 — psychoses. Malnutrition can be a direct cause, whether in Age (years) 1.28** 1.11 to 1.47 childhood or as an adult (for example, pellagra). Rarely, 16-24 endocrine disorders such as myxodema may be causative. 25-34 1.00 — Occupational and environmental causes include infection (for 35-44 1.14 0.89 to 1.45 example, encephalitis), the toxic effects of exposures at work 45-54 1.27 0.99 to 1.64 (for example, mercury poisoning), and trauma (head injury). 55-64 1.31* 1.01 to 1.69 0.71* 0.53 to 0.94 Psychological factors—for example, poor coping skills and Family unit type persistently low self esteem—also contribute. Such routine Couple, no children 1.00 — adverse life events as bereavement or job loss can lead to at Couple with 1 ϩ children 0.89 0.75 to 1.06 least temporary mental disorder in the vulnerable. Unusually Lone parent ϩ child 1.41* 1.08 to 1.83 distressing or life threatening events may predispose towards One person only 1.23* 1.00 to 1.51 the development of post-traumatic stress disorder. Such Adult with parents 0.44 0.26 to 0.75 mechanisms are exacerbated by inadequate social support Adult with one parent 0.71* 0.53 to 0.95 networks. Chronic social adversity (unemployment, poverty, illiteracy, child labour, violence, and war) is also often Employment status 1.00 — responsible, especially among underprivileged people. Working full time 1.16 0.96 to 1.39 Working part time 1.44* 1.02 to 2.01 Longitudinal studies have shown that unemployment, Unemployed 2.26** 1.92 to 2.66 redundancy, or even the threat of redundancy cause mental Economically inactive illness, although naturally, employees who are already mentally 1.00 — ill are more likely to lose their jobs—either voluntarily Tenure 1.41** 1.22 to 1.64 or involuntarily. Given what is known about the mean rates of Owner-occupier illness in the population as a whole and a higher rate in the Renter 1.00 — unemployed, one would expect to find comparatively lower 1.16* 1.01 to 1.34 rates of illness in people at work. However, those studies that Locality have been done in particular groups of workers have shown Semi-rural or rural quite high rates of mental illness. It has been suggested, Urban 46

Mental health at work however, that some bias may have occured in studying working Difficulties in activities of daily living in household samples populations that were chosen because they are perceived to be particularly stress prone. The table on page 46 shows the People assessed as having … % with any N strength of some of these risk factors in relation to mental Suicidal thoughts in the past week difficulties illness in the United Kingdom. Probable psychosis in the past year 45 Neurosis in the past week 59 54 The clinical interview schedule is a semistructured None of the above 58 1376 standardised clinical interview for use in epidemiological 41 5919 studies in the community, primary care, and workplace settings. 13 It was originally devised to be used by mental health researchers, but has since been revised for use by lay interviewers with no mental health training. Consequences Mental disorder is already prevalent within The development of mental illness is often followed by a series the workplace. Working conditions are known of psychosocial problems. Physical illness may occur, partly as a to have a considerable influence on mental result of self destructive behaviour. Suicide is now the tenth health. Therefore, to minimise the damage leading cause of death worldwide. A descent in the social order from this source to both employees and is common, and with this comes poverty and secondary effects employers, the most sensible course would on social relationships, especially family ones. These potential seem to be for employers to institute mental developments are paralleled by effects on working life—for health policies as part of their human example, loss of job status or unemployment. The employer resources framework incurs the costs of sickness absence, impaired productivity, and increased devotion of time to human resources issues. The Workplace mental health policy table shows the high level of social disability associated with mental disorder, both psychotic and non-psychotic. A workplace mental health policy is agreed between employers, employees, and their representatives—for example, trade unions, The role of the employer and includes: Whether or not a person’s illness is contributed to by work, their • A statement that the organisation is committed to a course of workplace bears the consequences of the illness in terms of action which might include reduced productivity, sickness absence, labour turnover, – increased understanding of causes of mental health problems accidents, and so on. It should be in the employer’s interest to in the workforce provide a good working environment, supportive if necessary, – action to combat workplace stressors and helping staff to and to enlist some kind of occupational health service to detect manage their stress and, sometimes, to help rehabilitate people with mental – action to manage mental health problems effectively through disorders in collaboration with other health and social agencies. early recognition and appropriate management In fact, such is the negative attitude of employers towards – action to manage the return to work of those who have potential employees with such an illness that, far from offering suffered mental health problems to ensure their skills are not support, they usually attempt instead to exclude. Mental lost to the enterprise disorders that have a substantial impact on everyday life are regarded as disabilities in the United Kingdom, and employers • Commitment to a healthy workforce, placing a huge value on are forbidden to discriminate unreasonably against such people both physical and mental health when offering employment. Instead, adjustments to working life must be entertained. • Acknowledging that mental health problems may have many causes, including stressors in the workplace and in the outside Less serious disorders that have little influence on everyday world life, and drug and alcohol dependence, which are not covered by the Disability Discrimination Act, may nevertheless cause • Listing factors that may lead to increased stress levels in the immense problems for employers and fellow employees. Mental organisation (customised, based on discussion with staff and disorders can be screened for but, rather like back pain, the needs assessment) lifetime prevalence is so high that excluding candidates with a history of mental disorder will simply reduce the potential • Recognising that domestic factors (such as housing, family workforce to unmanageable levels. Certain conditions, if problems, and bereavement) may add to levels of stress declared, do probably render applicants potentially unfit for experienced by employees certain occupations: psychotic illness, personality disorder, and substance abuse for the caring professions; personality disorder and dependency disorders in safety sensitive jobs. The role of Government To support a successful economy and to make an appropriate contribution to the prevention of discrimination against people with mental illness, government agencies and other national bodies may need to take action on environmental conditions at work; access to employment, including sheltered employment for those who need it; opportunities for employment rehabilitation; the promotion of workplace mental health 47

ABC of Occupational and Environmental Medicine policies; and the provision of occupational health for the Many schools now teach children “values”— workforce. This is especially important now that many respect for others’, feelings, acceptance of governments encourage the return to work of those who have differences in race, religion, etc. This can be suffered mental health problems, as well as those recovering established equally well in a workplace with a from physical illness as part of “welfare to work” schemes. In set of “company values” that go beyond the times of full employment this may well increase the proportion usually facile “mission statement” of those at work who are psychiatrically vulnerable. The role of schools in supporting subsequent occupational health initiatives Besides their primary educational role, schools are important Mental state examination settings for mental health promotion. They can teach children important life skills aimed at reducing acute and chronic social • Appearance and behaviour—Grooming, hostility, restlessness, stressors and enhancing social supports, all of which have a pupils, alcohol smell direct influence on mental health, and which may be expected to influence subsequent mental health in adult working life. • Communication—Rapid, sparse, confused Thus, employers as a body have an interest in encouraging • Mood—Low or high, feelings of self worth, hopelessness, mental health promotion in schools in the same way that they encourage mathematical and literacy skills, as well as physical concentration, biological aspects (sleep, energy levels, appetite, health. Such mental health promotion should include teaching libido), suicidal ideation of coping skills, citizenship skills, exam skills and techniques, • Thoughts—Thought formation, thought content stress management, achieving potential in relationships and • Perceptions—Hallucinations, etc. working situations, recognising and combating bullying, • Cognitive aspects—Orientation, short term memory, knowledge of learning to say no to risky behaviours, and education about current affairs, neurological deficits parenting and child rearing in collaboration with a health • Insight—Individual aware they are ill? Prepared to be treated? education and addiction programme. Diagnostic features of mixed anxiety and The role of health professionals depression Health professionals, including occupational health • Low or sad mood professionals, need to be adept at detecting and assessing • Loss of interest or pleasure mental health problems in the workplace. Managers may • Prominent anxiety or worry suspect mental health problems but they cannot be expected to • Multiple associated symptoms diagnose or assess them, and they need help from health • Disturbed sleep professionals in understanding and managing them. An • Tremor occupational physician should be able to take an adequate • Fatigue or loss of energy psychiatric history, identify any possible physical agents • Palpitations responsible or stressors (in or out of work), and then perform a • Poor concentration mental state examination to complete a risk assessment. • Dizziness • Disrupted appetite An occupational health professional’s most important and • Suicidal thoughts and acts unique contributions to helping manage people at work who • Dry mouth have had or are experiencing mental health problems are to try • Loss of libido to reduce stigma and discrimination, foster an understanding • Tension and restlessness among managers and work colleagues, and advise on adjustments • Irritability to the workplace when employees decompensate or when they return after a period off work because of mental illness. The high rate of suicidal thoughts in people with depression means that teaching good assessment and management techniques to health and social care professionals should be a priority, as should national and local action to minimise environmental risk factors for suicide. Common mental disorders that may present in the workplace Mixed anxiety or depression Mixed anxiety or depression is the commonest disorder seen in occupational settings. People with this disorder may present with one or more physical symptoms—for example, various pains, poor sleep, and fatigue, accompanied by a variety of psychological symptoms. It is a prime cause of absence from 48

Mental health at work work “due to stress.” Together with related states, it contributes considerably to the disability accompanying musculoskeletal disorders, especially back pain, and to fatigue states. Depression Diagnostic features of depression • Low or sad mood Depression is common, with a lifetime prevalence in the • Loss of interest or pleasure United States of 17% for a major episode. The sufferer may • At least four of the following: present with physical symptoms, irritability, anxiety or insomnia, worries about social problems such as financial or marital – disturbed sleep difficulties, increased drug or alcohol use, or (in a new mother) – disturbed appetite constant worries about her baby or fear of harming the baby. – guilt or low self worth Some groups are at higher risk—for example, those who have – pessimism or hopelessness about future recently given birth or had a stroke, and those with physical – decreased libido disorders such as Parkinson’s disease or multiple sclerosis. – diurnal mood variation – poor concentration Differential diagnosis – suicidal thoughts or acts The differential diagnosis includes acute psychotic disorder if – loss of self confidence hallucinations or delusions are present; bipolar disorder if – fatigue or loss of energy there is a history of manic episodes; poisoning or substance – agitation or slowing of movement or speech misuse if heavy alcohol or drug use has occurred; and chronic • Symptoms of anxiety or nervousness are also frequently present mixed anxiety-depression. Some medications may produce symptoms of depression (for example, ␤ blockers, other Essential information about depression for patient, family, antihypertensives, H2 blockers, oral contraceptives, work colleagues, and managers corticosteroids). Unexplained somatic symptoms, anxiety, or • Depression is a common illness and effective treatments are alcohol or drug disorders may coexist with depression. available Alcohol and drug misuse • Depression is not weakness or laziness • Depression can affect a person’s ability to cope Employees (or employers) with alcohol problems may present Information leaflets or audiotapes can be used to reinforce the with depression, nervousness, insomnia, physical conditions information such as peptic ulcer, gastritis, liver disease, hypertension, accidents or injuries, poor memory or concentration, and Alcohol dependency evidence of self neglect (for example, poor hygiene). They may The presence of three or more of the following suggests be people in whom treatment for depression has failed. alcohol dependency Patients may also have legal and social problems resulting from • Strong desire or compulsion to use alcohol alcohol—for example, marital problems, domestic violence, • Difficulty controlling alcohol use child abuse, or missed work. Signs of alcohol withdrawal may be • Withdrawal (anxiety, tremors, sweating, hallucinations) when present—for example, sweating, tremors, morning sickness, hallucinations, and seizures. Those with alcohol problems often drinking has ceased deny or are unaware of their problems, and it may be others • Tolerance—drinking large amounts of alcohol without appearing who request professional help. intoxicated Management by the occupational health department • Continued alcohol use despite harmful consequences Employees may be referred with a suspicion of an alcohol Presentation of alcohol problems at work problem or the possibility may be raised at the first interview. • Poor attendance—frequent sickness absence, certified or Assessment may be aided by simple well validated screening questionnaires such as the CAGE questionnaire and, for less uncertified—may be regular—for example, after weekends or excessive but still harmful drinking, the alcohol use disorders breaks identification test (AUDIT) questionnaire. • Lateness for work • Poor performance—mistakes, slowness, poor judgement, The assessment should be conducted in a straightforward frequent mishaps non-judgmental way and cover drinking pattern, amount, type, • Prolonged lunch hours, afternoon sleepiness circumstances, and duration, as well as symptoms; convictions • Poor personal hygiene, scruffiness, smelling of alcohol for drink driving should be specifically asked about. Laboratory • Irrational or noisy behaviour, inappropriate comments, tests may help diagnosis but have a limited use in isolation. irritability They can help in patient education and in monitoring alcohol • Frequent disappearances during the day reduction, as can a drink diary. • Signs of violence—cuts and bruises • Dishonesty or deviousness Managing alcohol problems at work • Frequent sickness absence because of gastrointestinal upsets This is best done in the context of an alcohol and drugs policy at work, which will always include a ban on the use of illegal drugs at work but which may have a variable attitude to alcohol at work, perhaps allowing alcohol to individuals whose jobs are not safety sensitive, for social occasions, or after the working day is over, etc. Whatever the policy, it needs to be signed up to 49

ABC of Occupational and Environmental Medicine by management and workers’ representatives. If there is an CAGE questionnaire Occupational Health Department or some kind of welfare service, then referrals by managers or individuals themselves Four questions: for alcohol related problems should be possible, and the • Have you ever felt you ought to Cut down on your drinking? condition treated initially as a health problem, and only when • Have people Annoyed you by criticising your drinking? there is refusal or inability to stop or reduce drinking to • Have you ever felt bad or Guilty about your drinking? reasonable levels are disciplinary procedures invoked. Time off • Have you ever had a drink first thing in the morning to steady work as sick leave may be required. Referral to a general practitioner or alcohol misuse specialist will be necessary. your nerves or get rid of a hangover (“Eye-opener”)? Compliance with undertakings can be managed by an occupational health department, using random testing if Over 90% of dependent drinkers answer “yes” to two or more of required. The same process can be used for employees who use these questions illegal drugs, although the very illegality of the drugs can lead to disciplinary measures much more quickly. Alcohol use disorders identification test (AUDIT) Both alcohol and drug abuse are chronic conditions, and See Saunders JB, Aasland OG, Babor TF, de la Fuente JR, Grant M. any employer or Occupational Health Service has to realise the Development of the alcohol disorders idenitfication test (AUDIT): high probability of relapse, although research shows that WHO collaborative project on early detection of persons with rehabilitation is more likely to be successful when the problem harmful alcohol consumption. Addiction 1993;88:791-803 is dealt with in a work context when the individual is threatened with potential job loss. Early recognition, Management of alcohol dependence assessment, and active management of the situation also help. Essential information for employees, managers, and families Alcohol and drug abuse is a serious problem for society and • Alcohol dependence is an illness with serious consequences is clearly increasing in incidence; it is also a huge problem for • Ceasing or reducing alcohol use brings mental and physical employers. The yearly cost to industry of alcohol misuse has been estimated at about £3 billion in the United Kingdom through benefits accidents, reduced productivity, and absenteeism. Hangovers • Drinking during pregnancy may harm the baby alone have been estimated to cost industry £50-100 million. • For people with alcohol dependence, physical complications of Drugs of abuse other than alcohol can have serious effects alcohol abuse or psychiatric disorder, abstinence from alcohol is on performance, probity, and so on. Testing for drugs at pre- the preferred goal employment or randomly is practised in some safety sensitive • In some cases of harmful alcohol use without dependence, or industries. The testing has to be done using proper chain of where the individual is unwilling to quit, controlled or reduced custody techniques and in the context of an agreed drugs drinking is a reasonable goal policy, which may or may not allow for rehabilitation while still • Relapses are common. Controlling or stopping drinking often employed. Employers and occupational health professionals requires several attempts. Outcome depends on the motivation who undertake coercive testing for drugs of abuse must ask and confidence of the patient themselves whether by instituting this programme they are Advice and support to patient and family trying to exclude “undesirables” from this workplace or to • Discuss costs and benefits of drinking from individual’s identify those who, while under the influence of drugs, may perspective present a safety or security risk? This issue raises concerns • Give feedback about health risks, including the results of gamma about human rights. glutaryl transferase and mean corpuscular volume measurements • Emphasise personal responsibility for change and give clear advice Women’s issues • Consider targeted counselling For patients willing to stop now Women, by virtue of their increased exposure to acute life • Set a definite day to quit events, chronic social stresses, lower social status and income, • Discuss symptoms and management of alcohol withdrawal and smaller social networks, are often particularly vulnerable to (may require time off or even hospitalisation) common mental disorders. This is reflected, hardly surprisingly, • Discuss strategies to avoid or cope with high risk situations in higher rates of sickness absence because of psychological (for example, how to face stressful events without alcohol, causes. Disorders associated with menstruation, pregnancy, and ways to respond to friends or colleagues who still drink) childbirth are additional disorders specific to women. New • Help identify colleagues, friends, and family who will support mothers often feel pressured to return to work early after ceasing alcohol use childbirth, and one of the most important preventive actions • Discuss support after withdrawal that can be taken in the mental heath arena is to recognise • Mention self help organisations such as Alcoholics Anonymous, postnatal illness and ensure adequate and prompt treatment. which are often helpful Eating disorders Concern has arisen that a history of such disorders makes candidates unsuitable for caring professions such as nursing or An eating disorder may be declared at a pre-employment school teaching, but this is not necessarily the case. In this screening. The two main types, anorexia and bulimia, of which context, attention should be paid to any accompanying the latter is more common, occur mainly in young women. An behavioural disorders including self harm—for example, and individual may present with binge eating and extreme weight personality disorders, rather than uncomplicated eating control measures such as self induced vomiting, and excessive disorders use of diet pills and laxatives, usually covert. In the case of employees, management may ask occupational health professionals for help because of concerns about an 50

Mental health at work individual’s weight loss. Both anorexia and bulimia may present Diagnostic features of bipolar disorder as physical disorders (for example, seizures or cardiac arrhythmias) that may have employment consequences and Periods of mania characterised by need treatment. Bulimia is, in general, a much more transitory • Increased energy and activity condition with a better record of successful treatment. • Elevated mood or irritability Anorexia nervosa is often more chronic and intractable and • Rapid speech may involve prolonged sickness absence because of • Loss of inhibitions hospitalisation. • Decreased need for sleep • Increased importance of self Bipolar disorder • Persistent distraction Patients may present with a period of depression, mania, or Periods of depression characterised by excitement, or referral may be made by others because of the • Low or sad mood individual’s lack of insight. • Loss of interest or pleasure • Disturbed sleep The diagnostic features of bipolar disorder are given in the • Guilt or low self worth box. Periods of either mania or depression may predominate. • Fatigue or loss of energy Episodes may alternate often or may be separated by periods of • Poor concentration normal mood. In severe cases, patients may have hallucinations • Disturbed appetite (hearing voices or seeing visions) or delusions (strange or • Suicidal thoughts or acts illogical beliefs) during periods of mania or depression. The differential diagnosis includes poisoning or drug or alcohol Further reading misuse, which may cause similar symptoms. • World Health Organization collaborating centre for research and Individuals often enter the hypomanic state rapidly, with training for mental Health, eds. WHO guide to mental health in danger to themselves and to others at work, especially if their primary care. London: Royal Society of Medicine Press, 2000.This job is safety sensitive. Some kind of early warning system should is a pocket guide for the assessment, diagnosis, management, and criteria be instituted by the Occupational Health Department with the for referral of common mental disorders at primary care level. It has been individual’s consent and the cooperation of managers or specifically tailored for the United Kingdom by the WHO Collaborating sympathetic work colleagues. Centre at the Institute of Psychiatry and contains the evidence base, resources including voluntary agencies, and a discussion of how to audit High risk occupations training needs Certain occupations are at high risk for work related mental • Andrews A, Jenkins R. Management of mental disorders. Aldershot: illness (and, incidentally, for fatigue states). These include Datapress, 2000.This is a two volume manual for the management of occupations such as teaching, nursing, and the police force mental disorders, and is suitable for all members of the multidisciplinary where there is a need for emotional commitment in the team. It contains specific guidance on psychological therapies personal problems of other people and where there are considerable staff shortages, high demand, and poor locus of • Jenkins R, Bebbington P, Brugha TS, Farrell M, Lewis G, control. Meltzer H. British psychiatric morbidity survey. Br J Psych 1998;173:4-7. This paper summarises the key findings from the first Certain occupations are also at high risk for suicide. These national survey of psychiatric morbidity in Britain. It shows the high include vets, doctors, dentists, pharmacists, and farmers—they prevalence of the psychiatric disorder and its association with have greater access to the means of suicide and better sociodemographic and social risk factors knowledge about effective methods of suicide, as well as being in demanding occupations. • Jenkins R, Macdonald A, Murray J, Strathdee G. Minor psychiatric morbidity and the threat of redundancy in a Health professionals lead stressful lives, and epidemiological professional group. Psych Med 1982;12:799-899. This paper shows studies have confirmed the high levels of depression and the psychiatric impact of the threat of redundancy on Times journalists anxiety in healthcare staff, indicating the need to address the support of this key group. • Jenkins R. Minor psychiatric morbidity and labour turnover. Br J Ind Med 1985;42:534-9. The paper shows that the presence of minor Employers are becoming increasingly worried—mainly for psychiatric morbidity (depression and anxiety) is associated with legal reasons—about the effect of demanding work on the substantially increased labour turnover, with associated costs for employers mental health of vulnerable employees. This is a contentious area with little in the way of legal precedent but one where • Jenkins R. Minor psychiatric morbidity in civil servants and its advice is frequently asked of occupational health professionals. contribution to sickness absence. Br J Ind Med 1985;42:147-54. Careful psychological assessment, knowledge of the job This paper describes the substantial association between minor psychiatric stressors, and a traditional risk assessment approach offer the morbidity and sickness absence both retrospectively (the 12 months before best way forward. Attempts have been made, using a partially the assessment) and projectively (the 12 months after the assessment), evidence based approach, to define health standards, including again with associated costs for employers medical criteria, for entry into certain demanding professions—the armed forces, medicine, nursing, teaching, • Jenkins R, Warman D, eds. Developing mental health policies in the and civil emergency services. This can be helpful. workplace. London: HMSO, 1993 The potential for violence and bullying at work has also • Jenkins R, Coney N. Promoting mental health at work. London: concerned employers, but such behaviour does not in fact HMSO, 1992. These two books look at the business case for action to usually emanate from those with mental illness but from develop mental health policies in the workplace, from the CBI and TUC those with problematic personality types or drug and alcohol perspective, and examines a range of good practice examples from problems. different companies • Department of Health. ABC of mental health in the workplace. London: HMSO, 1996. This government publication sets out the key elements of a workplace mental health policy • Jenkins R. Public policy and environment. In: Gelder M, ed. Oxford textbook of psychiatry. Oxford: Oxford University Press, 2000. This chapter sets the issue of mental health in the workplace in the context or overall public policy and mental health • Miller DM, Lipsedge M, Litchfield P, eds. Work and Mental Health—an employer’s guide. Gaskell and Faculty of Occupational Medicine, 2002. Straightforward and comprehensive account of the impact of mental health problems on work and how to deal with them. 51

ABC of Occupational and Environmental Medicine The third area of concern is safety. The potential problems The table showing the prevalence of psychiatric disorders and the table with psychotic or dementing employees and employees who showing rates of mental illness employed and unemployed are adapted misuse drugs or alcohol will be obvious. The assessment of less from ONS survey of psychiatric morbidity among adults living in private serious mental disorders and their relation to safety is a job for households. London: HMSO, 2000. The table showing the prevalence of the occupational physician using a similar approach to that mental disorders in the workplace is adapted from Jenkins R. Public described for assessing those entering demanding jobs. policy and environment. In: Gelder M, ed. Oxford textbook of psychiatry. Psychotropic medication often affects cognition, especially at Oxford: Oxford University Press, 2000. The table showing risk factors the beginning of treatment; drowsiness and lack of associated with common mental disorders and the table showing concentration are common and should be anticipated. difficulties in activities of daily living are also adapted from ONS survey of psychiatric morbidity among adults living in private households. Mental ill health at work is likely to become the dominant London: HMSO, 2000. occupational health issue of the future. There is enormous scope for research and enormous need for public education and the destigmatisation of mental illness. 52

10 Human factors Deborah Lucas The term “human factors” is often invoked after an accident, “Human error” is often cited immediately after a disaster whether a minor incident in the workplace or a major disaster entailing significant loss of life. In many respects “human Examples of human failures in medicine factors” is regarded by the layman as being synonymous with • A patient is inadvertently given a drug that they are known to be “human failure”—an unavoidable aspect of the human condition. Although there is a long list of major accidents allergic to across all hazardous industrial sectors where human failures were causal factors, this is not to imply that human errors are • A clinician misreads the results of a test inevitable. Research over the past 20 years has shown much • A child receives an adult dose of a toxic drug about the origins of different types of error and the best means • A patient is given medicine that has a similar sounding name to of reducing their occurrence. However, the loss of life in disasters such as the Clapham Junction rail crash in 1988, the that prescribed Southall and Ladbroke Grove train crashes in 1997 and 1999, respectively, and the sinking of the Herald of Free Enterprise in • A toxic drug is administered by the wrong route—for example, 1987 are high in the British public’s mind. All of these disasters had human factors as a cause: a maintenance worker not intrathecally disconnecting a wire, a train driver passing a red danger signal, and a bosun failing to close the bow doors of a ferry. The • A heart attack is not diagnosed by emergency room staff in an nuclear industry faced up to the issue of human factors after Three Mile Island in 1979 and the Chernobyl accident in 1986. older patient with ambiguous symptoms The oil sector recognised the issue after the Piper Alpha tragedy in 1988. The aviation, rail, and marine transportation Common errors relating to drugs sectors are all actively considering the issue of human factors. • Unavailable drug information (for example, lack of up to date Proper consideration of human factors is a key ingredient of effective health and safety management in all industrial warnings) sectors. • Miscommunication of drug orders (for example, through poor Modern health care is also a complex and, at times, high risk activity where adverse events are inevitable. However, a handwriting, confusion between drugs with similar names, substantial proportion of adverse events results from misuse of zeros and decimal points, confusion between preventable human failure by medical staff. Adverse events milligrams and micrograms) occur in about 10% of admissions to hospital in the United Kingdom—a rate of 850 000 adverse events a year. In the United • Incomplete patient information (such as not knowing about Kingdom, 400 people die or are seriously injured every year in adverse events involving medical devices. Hospital acquired other medicines they are taking) infections are estimated to cost the NHS nearly £1 billion every year, but about 15% of such infections may be avoidable. In the • Lack of suitable labelling when a drug is repackaged into smaller United States it is estimated that between 44 000 and 98 000 people die annually because of medical errors. Yet health care is units not unique. There are many parallels with other high risk sectors, which have been examining the need to reduce human • Workplace factors that distract medical staff from their immediate failures in complex systems for over two decades. tasks (such as poor lighting, heat, noise, and interruptions) Definition Human factors are often described as the thread that runs through all the key health and safety management issues, and numerous definitions of human factors and the related term ergonomics exist. The definition given by the UK Health and Safety Executive is “Human factors refer to environmental, organisational and job factors, and human and individual characteristics, which influence behaviour at work in a way that can affect health and safety.” Key elements have been identified by psychologists and ergonomists after an incident or accident, and in the military field human factors programmes explicitly consider six aspects or domains during the design or procurement of a system. These domains have been found to be useful in other industrial contexts. 53

ABC of Occupational and Environmental Medicine Human factors considered in the development of military systems Domain Issue Issues to consider Staffing How many people are needed to operate Workload and maintain the system? Job descriptions Staffing levels Personnel What human characteristics, including aptitudes Team organisation Training and experience, are needed to operate and maintain the system? Selection and recruitment Career development What is the best way to develop and maintain Required qualifications, competences, and experience the required knowledge, skills, and abilities Specific characteristics to operate and maintain the system? Training needs analysis Human factors How can human factors be built into the Documentation engineering system design to optimise human Assessment performance? Team training Skill maintenance and update Health hazards What are the short term and long term health System safety hazards from operation of the system? Equipment design Workstation design How can safety risks that humans might cause when Workplace layout operating or maintaining the system be avoided? User interface design Maintenance access Minimising exposure to health hazards such as toxic materials, electricity, musculoskeletal injury, noise and vibration, extremes of temperature Sources of human errors Effects of misuse of equipment Abnormal and emergency situations Human failure Typical causes of human failures in accidents Research across industries has shown much about the types of Job factors human failure and the underlying psychological mechanisms. A key distinction can be made between unintended human • Illogical design of equipment and instruments errors and deliberate rule violations. However, even deliberate • Constant disturbances and interruptions violations can result from system pressures such as shortage of • Missing or unclear instructions time because of a lack of staff, or the correct equipment not • High workload being available. In high hazard industries it is no longer • Noisy and unpleasant working conditions acceptable to attribute a safety incident just to a “human error” with the assumption that this was somehow beyond the control Individual attributes of managers and safety management systems. A detailed • Low skill and competence levels E.1 Skill based errors E.1.1 Slips of action • Tired staff (\"absentmindedness\"): for example, transposing digits, • Bored or disheartened staff occur in very familiar misordering steps in a procedure • Individual medical or fitness problems task when attention is diverted E.1.2 Memory lapses Organisational aspects for example, omitting steps in a E.2 Mistakes (planning procedure, losing place when • High work pressure because of poor work planning and decision making interrupted • Poor health and safety culture failures): occur when • One way communications (messages sent but no checks to planning and reasoning E.2.1 Rule based mistakes go awry for example, using familiar rule or ensure they are received or are appropriate) procedure thinking it is appropriate for the situation • Lack of safety systems and barriers • Inadequate responses to previous incidents E.2.2 Knowledge based mistakes E Errors: for example, misdiagnosing or unintended miscalculating when reasoning actions from first principles or decisions Not known Slip/lapse Technical V.1 Routine: Organisational breaking rules is a normal way of working V Violations: Rule based deliberate deviation from V.2 Situational: rules or procedures caused by time pressures, the wrong equipment, and so on V.3 Exceptional: Knowledge based rarely happen and only when something has gone wrong; a rule is broken to solve a new problem Classification of the types of human failure Causes of incidents in a department of surgery 54

Human factors investigation into the causes of incidents involving human Case study: reducing errors in the administration of failure will show a number of immediate and underlying causes and contributing factors. Many of these will be problems with intravenous heparin organisational systems rather than with the individual member of staff. The intravenous administration of heparin (an anticoagulant) is a complex procedure, and this drug has been the subject of serious Control measures drug errors. A US hospital wanted to reduce errors in the administration of heparin in cardiac care units. They developed There is no “magic bullet” for the problems of human fallibility. a form that combined the ordering and recording of the use of However, thoughtful, multifaceted approaches can reduce the heparin. In addition, they improved communication with the probability of human failures leading to serious consequences. hospital laboratory, converted all heparin protocols to pharmacy In medicine, knowledge and tools to enhance patient safety are managed protocols, introduced pre-typed heparin orders and the emerging, and much can be learnt from other industries, double-checking of pump programming, and encouraged the use particularly the high hazard sectors such as the nuclear of low molecular weight heparin instead of standard heparin. industry, aviation, and transportation. These control measures were claimed to have reduced drug errors by 66% Designing for people “Human beings make mistakes because the systems, tasks, and processes they work in are poorly designed” Many sources of human error can be removed through Dr Lucian Leape, testifying to the US President’s Commission effective design of equipment and procedures. Such “error on Consumer Protection and Quality in Health Care tolerant” designs consider the tasks that the equipment is intended for and the errors the user may make. To give an Examples of ergonomic criteria for procuring equipment example, in the early days of automatic teller machines, the • Does the equipment suit the body size of all users? user’s bank card was returned to them by the machine after • Can users see and hear all they need to easily? their cash had been issued. Banks found that many people took • Is it easy to understand the information displayed? their money but forgot to take their card. This error was • Would the equipment cause discomfort if used for any length of prevented by returning the card before the cash appeared. time? Consideration of human factors is an important aspect of overall design and equipment procurement, and should be • Is it easy to learn how to use the equipment? Are instructions considered early in the design process. If left too late, then complicated procedures, added warnings, and requests for the and any warning signs clear? Is the language used appropriate user to “take care” can be the unfortunate result. Compliance for the users? with instructions and procedures differs according to the situation, the risks, the element of personal choice, and • What errors may occur? Can these be detected easily, and the probability of being detected. Written warnings are usually noticed, read less often, and complied with corrected? infrequently. • Is the equipment compatible with other systems in use? Poorly designed equipment can directly influence the • Can users reach controls easily? chance of human errors occurring. For example, the layout of • Can users move safely between operating positions? controls and displays can influence safety if switches are placed • Is the equipment too noisy, does it vibrate too much, is it paced so that they can inadvertently be knocked on or off, if controls are poorly identified and can be selected by mistake, or when too fast? critical displays are not in the user’s normal field of view. The controls of different equipment may not be compatible: for example, a switch in the up position may be “on” in one % compliance 90 80 70 Taking Cyclists Wearing 60 medicines stopping personal safety 50 at red lights 40 equipment 30 20 10 0 Wearing seat belts Compliance rates in different situations Arrangement of controls on a lathe and the “ideal” operator, who should have the following dimensions—4 feet 6 inches tall, shoulders 2 feet across, and an 8 foot arm span! 55

ABC of Occupational and Environmental Medicine case but “off” in another. Alarm systems may be designed so The relationship between sleepiness and accidents: best that high priority alarms are not clearly differentiated and are practice approaches to managing the problem thus easily missed. • Plan shift rosters to take biological rhythms into account • Set limits for maximum hours of duty and time needed for Designing tasks, equipment, and workplaces to suit the users can prevent or reduce human errors and thus reduce recovery afterwards accidents and ill health. A key message is that effective use of ergonomics will make work safer and more • Educate shift workers on sleep routines, nutrition, and exercise productive. • Make environmental changes to the workplace including Sleep and human performance lighting, temperature, and comfort level, which can all influence alertness Although it is often feasible to prevent human failures by the effective design of jobs and equipment, in other situations • Plan safety critical tasks to avoid night shifts human performance problems may arise as the result of • Provide medical advice for shift workers fatigue, shiftwork, poor communications, lack of experience, or • Recognise the possibility of true sleep disorders (sleep apnoea, inadequate risk perception. These aspects all need to be managed effectively to reduce the potential risks. One of the narcolepsy) and referral for investigation and treatment most commonly cited problems is lack of sleep for staff carrying out safety critical tasks. The decision to launch the High hazard industries are becoming increasingly aware of the importance Challenger space shuttle was partly attributed to the effects of of proper consideration of human factors fatigue on the decision making team. The rail crash at Selby in the United Kingdom in 2001 occurred because a car driver fell asleep and drove onto a railway line. A significant proportion of road traffic accidents occur between 2 am and 5 am and are attributed to drivers falling asleep at the wheel. As we are not a nocturnal species, this is the time when our biological clock programmes us to sleep. Such circadian rhythms are hard to adjust to, even when working regular night shifts. Many people work shift systems, do night work, or work very extended hours including significant levels of overtime. Such working patterns can have adverse effects on their health as well as being associated with poorer performance on tasks that need attention or sustained vigilance, decision making, or high levels of skill. Sleep is a powerful biological need, and night work or certain shift systems can disrupt both the quantity and the quality of sleep. Sleeping during the day is never as satisfactory as sleeping at night. Sleep loss of just a few hours over a few days can lead to a build up of a sleep debt and reduced performance, but the person may not be aware of this. A large body of research on shiftwork exists, but often the findings are not put into practice. Working patterns are usually seen as matters to be negotiated between employees and the employer, and additional overtime can be perceived as a financial advantage, and not as a potential health and safety issue. However, in high hazard industries awareness of the relation between sleepiness and accidents is growing. Organisational influences The Herald of Free Enterprise sank because no effective system was in place to ensure the bow doors were closed A number of factors within an organisation are associated with good safety performance. These affect not only human factors issues but also the “safety culture” of the organisation. A “culture” means shared attitudes, beliefs, and ways of behaving. An effective culture will be shown through good ways of informing and consulting all staff, recognition that everyone has a role to play in safety, visible commitment by managers to involving all staff, cooperation between members of the workforce, open two way communications, and high quality of training. The organisation that continually improves its own methods, and learns from mistakes (including accidents and “near misses”) will tend to have a better safety performance than one that blames individuals for “being careless” when accidents happen. 56

Human factors Key principles Further reading Human factors is a broad concept that can be seen as too • NHS. An organisation with a memory. London: NHS Publications, complex or difficult to do anything about. However, there are five key principles to be remembered, and these are ones that 2000 many regulatory bodies are promoting: • Reason J. Human Error. Cambridge: Cambridge University Press, • Recognise that people do not make mistakes because of “carelessness” and accept that even the most experienced 1990 members of staff are vulnerable to unintentional errors. • van der Schaaf TW, Shea CE. MECCA: Incident reporting lessons • Learn from adverse events including “near misses.” Understand that usually there will be no single cause of an from industry applied to the medical domain. Conference on incident but a number of causes and contributing factors. examining errors in health care, California: Rancho Mirage, 1996 • Anticipate the influences on human performance. Key themes will include time pressure, experience, staffing levels, • Reason J. Managing the risks of organisational accidents. Ashgate fatigue, and risk communications. Publishing, 1997. Seminal work on the causes of major accidents. A key • Defend against paths to failure. In particular, appreciate the role of designing equipment and systems that are error influence for those looking at medical errors tolerant. • Institute of Medicine. To err is human: building a safer health system. • Encourage a “culture of safety.” Washington DC: IOM, 1999. Significant US report on medical errors; draws attention to the scale of the problem of potentially avoidable events that result in unintended harm to patients • Building a safer NHS for patients. London: NHS Publications, 2001. Describes how promoting patient safety by reducing error is becoming a key priority of health services around the world. Sets out steps to implement a programme to reduce the impact of error within the NHS • HSE. Reducing error and influencing behaviour. Sudbury: HSE Books, 1999. Guidance to industry on understanding and control of human factors in health and safety management. Covers understanding human failures, designing for people, and control measures for human errors • Noyes J. Designing for humans. London: Taylor and Francis. 2001. Overview of human-machine interaction and the design of environments at work, with focus on health and safety at work • Moore-Ede M. The 24-hour society: the risks, costs and challenges of a world that never stops. London: Piatkus, 1993. Introduction to the role of sleep in accidents. Covers biological aspects of sleeping and shiftwork 57

11 Physical agents Ron McCaig The use of the term “physical agents” is not always clear. The effects of physical agents have been well Sometimes it is taken to mean dusts and fibres whose effects are studied, and for many of these exposure determined by their physical properties as well as their criteria are now established at an chemical composition. However, the term usually refers either international level. Fatalities are only likely to to those agents that impart energy to the body by physical occur where established safety procedures are means (for example, the effects of radiation, heat, or noise and broken vibration), or to the effects of environments that differ in their physical characteristics from that existing at ground level on Authorities that set exposure standards for physical agents dry land (for example, found in diving and compressed air • International Standards Organisation (ISO) work, at altitude, and in flight). • American Conference of Governmental Industrial Hygienists The body offers some protection against physical agents (ACGIH) experienced in the normal environment, such as heat and radiation—for example, by the physiological changes of heat • International Commission on Radiological Protection (ICRP) acclimatisation or, at a cellular level, the operation of DNA • International Commission on Non-Ionising Radiation Protection repair mechanisms. Such mechanisms are limited in their effectiveness and can be overwhelmed if challenged by an (ICNIRP) exposure of sufficient magnitude. Even in artificial environments, such as work in compressed air tunnelling or • Other national, transnational, and international authorities high accelerations in flight, it is possible that a certain amount of physiological adaptation can take place. For example, the The principles of managing work in hot environments incidence of decompression illness often reduces after the first • An assessment of the risk should be undertaken and ways sought few days of exposure of a work force tunnelling in compressed air—an effect that is thought to be a form of acclimatisation— to reduce the environmental heat load, paying attention to and some G tolerance can develop with physical fitness training. humidity and radiant heat, as well as air temperature Many physical agents have a threshold of exposure below • Individuals should be screened for medical conditions that may which the body is unlikely to be harmed. Beyond that, it is necessary to restrict exposures, often by administrative controls predispose to heat illness, and should be physically fit, well such as limiting the duration of exposure (as in work rest hydrated, and ideally below 40 years of age schedules in the heat), providing shielding or protective clothing and equipment, or limiting the potential for harm by • Work-rest regimes should be established from published procedures such as staged decompression. Exposures must be carefully managed as some physical agents can kill within quite standards and adhered to, with regular opportunities taken for short periods. the worker to cool down Before exposure to hot, cold, or hyperbaric environments it • Workers should be educated about heat illnesses, and first aid is important to ensure that individuals have no predisposition to suffer from the effects of the environment. Fitness standards facilities should be available may be available, published by a variety of agencies. For ionising radiation it is important to know that individuals are medically • In planning work, the state of acclimatisation of the workers and fit for the type of work that they are expected to perform. (They may need to wear protective equipment—for example.) the resistance to heat loss provided by their clothing has to be taken into account Heat Heat acclimatisation increases the magnitude of these responses. Any factor that impairs Regulation of the central (core) body temperature is an either the circulation or the ability to sweat essential physiological function—core temperature must be will compromise thermoregulation within the range 36-38ЊC for the body to perform efficiently. In the face of heat gain from the environment or as a result of exercise, the body defends the core temperature by vasodilatation (increasing skin blood flow) and by sweating. If heat gain is greater than heat loss by the evaporation of sweat, convective cooling, and thermal radiation, then the body stores heat. As it does so, the temperature of the brain and central organs (such as the liver)—the core temperature— increases and this threatens the survival of the individual. Eventually external cooling must be provided to prevent death. Heat hyperpyrexia (heat stroke) is the most serious effect of exposure to heat. It is generally characterised by a body 58

Physical agents temperature of 40-41ЊC, an altered level of consciousness, and Groups of people at risk from heat illness a hot dry skin resulting from failure of the sweating • Unacclimatised workers in the tropics mechanism. These features are not invariable, however, so • Workers in hot industries who have had a break from exposure treatment should not be delayed if heat stroke is suspected. • Workers with an intercurrent illness • Workers in the emergency services—for example, fire or mines Heat exhaustion results from a combination of thermal and cardiovascular strain. The individual is tired and may stumble, rescue and has a rapid pulse and respiration rate. The condition may develop into heat stroke if not treated by rest, cooling, and • People undertaking very heavy physical activity—for example, fluids. Other effects are heat syncope (fainting), heat oedema, (often in the unacclimatised), heat cramps, and heat rash military recruits (prickly heat). Working in high temperatures can also result in fatigue and an increased risk of accidents. • People working even moderately hard at normal temperatures in Workers in fire and rescue services may be exposed to all enveloping protective clothing—for example, fire crews extreme heat in an unpredictable manner. Their safety dealing with chemical spills depends on proper selection, training, and monitoring of the duration of exposure. Personal heat stress monitors are not yet • Older people and the very young when ambient temperatures widely available, but their use in these circumstances may confer some benefit. are raised for prolonged periods Cold The wet bulb globe temperature • The wet bulb globe temperature (WBGT) index is an index of In cold conditions the problem is to balance heat produced by physical activity with heat lost to the environment. The rate of heat stress. It is derived from the natural wet bulb temperature heat loss depends on the insulation of the clothing and the (WB), the dry bulb temperature (DB), and the globe external climate, including air temperature and wind velocity. temperature (GT) (a measure of radiant heating) in the ratio: The windchill index (derived in units of kcal/m2/hour) relates to the risk of freezing of superficial tissues, and this, or the WBGT ϭ 0.7 WB ϩ 0.2 GT ϩ 0.1 DB related chilling temperature (expressed in ЊC), is quite widely used as a measure of the discomfort of cold conditions. • The WBGT index is measured using a “Christmas tree” array The insulation of clothing may be impaired by moisture in of thermometers, or purpose built electronic sensors and the form of condensed sweat or by precipitation. Protection is integrating apparatus generally easier in cold dry environments such as mountains or arctic regions than in cold wet conditions. The protection of • The index was originally derived to protect troops exercising individuals who are active in cold wet environments, and who need waterproof external garments, is only partly solved by the outdoors by relating environmental conditions to the risk of heat introduction of “breathable” fabrics. A particular problem illness. It has since been developed and used extensively in occurs in those environments where there is a risk of industry and is the basis for International Standard 7243 and immersion in cold water, with resulting catastrophic loss of guidance by the ACGIH. These documents give upper insulation. Where this risk can be anticipated—for example, in boundaries of WBGT value for continuous and intermittent work helicopter flights over water, protective immersion suits should of different intensities. Other standards apply in relation to be used. thermal comfort—for example, ISO 7730 Large numbers of workers are employed indoors in Heat stroke conditions of moderate to severe cold, mostly in food Heat stroke is a medical emergency. The body temperature should preparation and storage. Only a few people are exposed to cold be lowered by tepid sponging and fanning with cool air. in scientific and testing laboratories. Cold stores can operate at temperatures as low as Ϫ30ЊC. Workers in cold stores must be Intravenous fluids may be necessary. The following may provided with proper insulated clothing, and they must have predispose to heat exhaustion and heat stroke: regular breaks in warm conditions. A major problem in severe cold, indoors or outside, is to keep the hands and feet warm. • Obesity The necessary insulation is bulky, which is less of a problem for • Lack of fitness footwear than for hand wear. Mitts provide better thermal • Age 50 years or more protection than gloves, but limit dexterity. • Drug or alcohol abuse • History of heat illness Indoors, in moderately cold conditions—that is, • Drug treatment (for example, antihistamines, tricyclic temperatures below 15ЊC, it may also be hard to maintain comfort of the extremities, and exposure to draughts can be antidepressants, or antipsychotics) particularly troublesome. Limited evidence indicates that workers regularly exposed to cold conditions such as these may • Pre-existing disease of cardiovascular system, skin, have worse than average general health. gastrointestinal tract, or renal system Serious hypothermia should not occur in occupational settings. If there is a risk, people should not work alone, should Frostbite in an outdoor worker have good communications with others, and should be trained in first aid management of the effects of cold. Hypothermia is treated by slow rewarming using the individual’s own metabolism, and copious insulation, possibly supplemented by body heat from another person. 59

ABC of Occupational and Environmental Medicine The peripheral effects of cold are frost nip, frost bite, and Conditions that preclude work in moderate non-freezing cold injury. Frost nip appears as a white area on to severe cold the skin, and in frost bite the appearance is of marbled white frozen tissue that is anaesthetic to touch. Treatment is by slow • History of ischaemic heart disease rewarming, often using body heat. Non-freezing cold injury • Peripheral vascular disease often does not manifest until exposure to cold ceases, and it • Hypertension or Raynaud’s phenomenon results in warm painful swollen extremities, usually the feet. • Asthma Chilblains are a minor form of cold injury. • Metabolic disorders • Sickle cell disease Ionising radiation • Arthritis Ionising radiation displaces electrons from their normal orbits Doses and units of radiation around the nucleus of the atom. The resulting ionisation alters the nature of biological molecules, especially DNA, resulting in • Absorbed dose—the energy of ionising radiation a body absorbs, gene mutation or cell death. ␣ Small particles are relatively large and easily stopped. ␤ Small particles are small and can measured in gray penetrate up to a centimetre in tissue. Neutrons are smaller than ␣ particles but are much more penetrating. ␥ Small • Dose equivalent—an adjustment of the absorbed dose, using a radiation and x rays are packets of energy transmitted as electromagnetic radiation, and are highly penetrating. quality factor for the type of radiation involved, to take account of the effectiveness of the different types of radiations in External irradiation is that arising from a source—either harming biological systems; measured in sieverts a radiation generator, such as an x ray machine, or a radioactive substance—that is separate from the body. The irradiation • Effective dose—an integrated index of the risk of harm, derived ceases when the generator is switched off or the source is moved away or shielded. The body can be contaminated by by multiplying the dose equivalent for each of the major tissues particles of radioactive material that lie on the skin externally by a weighting factor based on the tissue’s sensitivity to harm by or are incorporated into the tissues, resulting in internal radiation. The weighted values are summed. The unit is the irradiation. The latter will persist as long as the radioactive sievert material is in the body. Alpha emitters such as plutonium are particularly harmful sources of internal irradiation. The probabilities of harm from exposure to ionising radiation derived by the ICRP Large doses of ionising radiation cause death by damage to the brain, gut, and haemopoietic system. Such exposures only Values are expressed as percentage risk per sievert dose received occur in the event of accidents or deliberate release in nuclear (the values in the table are multiplied by 10Ϫ2 SvϪ1 to give the warfare. Lower doses can damage the skin or the lens of the actual risk) eye. This may occur if sources are mishandled or exposures are prolonged—for example, in industrial radiography or Fatal cancers Whole population Working population interventional radiography. The direct effects of radiation are Hereditary disorders considered to have a dose threshold for their occurrence, and Total risk 5 4 the severity of the effect is related to the dose received. 1 0.6 6 4.6 The stochastic effects of radiation (including the induction of cancer and hereditary effects) do not have a threshold, and The ICRP recommends an effective dose limit of 20 mSv (averaged the likelihood of the effect is related to the dose. Risk estimates over a defined five year period) for workers, and 1 mSv per year for the stochastic effects of radiation have been derived from for the public. Limits are also set for exposure of the eye lens, the epidemiological studies (cancer) and animal studies skin, and the hands and feet. The dose limit for the fetus is the (hereditary effects). The most important epidemiological data same as the public dose limit of 1 mSv a year are from the Life Span Study of survivors of the atom bombs used in 1945. The risk estimates are published by a number of bodies of which the ICRP is the most influential. The ICRP also publishes dose limits derived from the risk estimates, and these are the basis of the statutory dose limits applied in many countries. Risk estimates and dose limits are regularly updated as the underlying science develops. Workers who are substantially exposed to ionising radiation are subject to regular medical surveillance. This is to ensure that they are fit for their proposed work with radiation—for example, the need to work with unsealed sources or to use respiratory protective equipment. They are also subject to dose monitoring. Exposure to ionising radiation should be as low as reasonably practicable (ALARP) by the provision of appropriate controls, including shielding and reduction of exposure time. As legislative controls have been tightened, so the typical exposure to ionising radiation of workers has fallen. In the United Kingdom, average annual occupational doses are 1-2 millisieverts per year (about the same as background radiation). 60

Physical agents Studies of large cohorts of workers occupationally exposed Typical magnetic and electrical fields to radiation consistently show a healthy worker effect. Typical magnetic fields Nevertheless, cases of cancer of types known to be produced by • Natural fields—70 microtesla (static) ionising radiation do occur in these populations, sometimes • Mains power—200 nanotesla (if not close to power lines), with a slight excess. Individuals may be compensated for such disease on the basis of presumption of origin or probability of 20 microtesla (beneath power lines) causation. • Electric trains—50 microtesla Electromagnetic fields • Cathode ray tubes—700 nanotesla (alternating) Electromagnetic fields with wavelengths shorter than 0.1 mm— Typical electric fields that is, ultraviolet and below, contain insufficient energy to break molecular bonds and so do not result in ionisation. This • Natural fields—200 V/m (static) “non-ionising radiation” does, however, have other frequency • Mains power—100 V/m (in homes), 10 kV/m (under large dependent effects on biological tissues. Broad divisions of this radiation include microwave and radio frequency radiation, as power lines) well as extremely low frequency, which includes the frequencies of power distribution. • Electric trains—300 V/m • Cathode ray tubes—10 V/m (alternating), 15 kV/m (static) At high frequencies—for example, microwaves used in communication systems—the main effect is tissue heating, a ICNIRP 1998 Exposure guidelines to time varying electric phenomenon made use of in the microwave oven. This effect is and magnetic fields quantified by the specific absorption rate of energy into the • These specify basic restrictions in terms of current density for body, and in most situations there are unlikely to be ill effects. This might not be the case where the individual is also working the head and trunk, whole body and localised specific hard, or is exposed to a hot environment. At lower frequencies absorption rates, and power density the effects of electric and magnetic fields are considered separately. Exposure to magnetic fields can set up circulating • Reference levels below which the basic restrictions are unlikely to currents within the body, which have the potential to interfere with physiological processes if sufficiently great. For example, be exceeded are specified in terms of electric field strength (E), muscle activation could potentially occur during magnetic magnetic field strength (H), magnetic flux density (B), and resonance imaging. Low frequency electric fields do not power density (S). These are given separately for occupational penetrate the body, but can generate charges on the body exposure and for the general public, with lower values for the surface. latter. Reference levels are also given for contact currents from conductive objects and for induced current in any limb Other recognised but rarer effects include the phenomenon of microwave hearing. Some people hear Exposure from mobile phones and base stations repeated clicks when exposed to pulsed sources of • Public exposures from base stations are low; typical power electromagnetic fields, usually radars. A visual illusion of flickering lights (magnetophosphenes) can be produced when densities have been measured as 1 mW/m2, with maximum the retina is exposed to intense magnetic fields. Exposure power densities of 10 mW/m2 standards, which reflect the frequency dependence of effects, have been derived to protect against the established effects of • For comparison, the ICNIRP public exposure guidelines are a electromagnetic fields. power density of 4.5 W/m2 at 900 MHz and 9 W/m2 at 1.8 GHz Since the late 1970s there has been increasing public concern about exposure to electromagnetic fields. This was • Power densities can exceed guidelines very close to the antenna, prompted by epidemiological studies of the association between childhood cancer and residential exposure to magnetic fields. and for this reason public access to these antennae has to be In 2001 the International Agency for Research on Cancer controlled concluded that there was limited evidence that residential magnetic fields increase the risk of childhood leukaemia, • Hand sets can generate power densities of up to 200 W/m2, but resulting in a classification of “2B” “possibly carcinogenic” for extremely low frequency magnetic fields. It is thought that any the resulting fields inside the body are appreciably less then risk relates to those exposed to fields at or above those measured externally 0.4 microtesla, which are relatively large. The UK Childhood Cancer Study (UKCCS), the world’s largest case control study Units for electromagnetic fields on the causes of childhood cancer, found no evidence to • Electric field strength (E)—volts per metre support the association between residential magnetic field • Magnetic field strength (H)—amps per metre exposure and childhood leukaemia or other cancers. Any real • Power density (S) (vector product of E and H)—watts per square effects must be very small in magnitude. metre Public concern also extends to the possible effects of exposure to electromagnetic fields from mobile phone hand • Magnetic flux density (B)—Tesla (1 Tesla is about equal to sets and base stations. In the United Kingdom an independent expert group was commissioned to study the evidence in 10 000 Gauss) relation to mobile phone technology. This group concluded that exposure to radio frequency radiation below the ICNIRP guidelines did not adversely affect population health, but in 61

ABC of Occupational and Environmental Medicine view of other biological evidence it concluded that it was not Possible effects of optical radiation on the eye possible to say that exposures below current guidelines were • Ultraviolet C/B—arc eye totally without potential adverse health effects. The group • Ultraviolet B—pigmentation of lens therefore advocated a precautionary approach in the use of this • Ultraviolet A—retinal damage in aphakia technology—for example,, suggesting that the use of mobile • Visible—accelerated ageing (high power sources), burns of phones by children for non-essential calls should be discouraged. retina (lasers) There is no evidence that exposure to electromagnetic • Infrared—corneal burns, usually prevented by blink reflex, fields from the use of display screen equipment has any harmful effects. cataract, retinal burns, from infrared A sources including lasers Optical radiations Wavelengths of optical radiation • Ultraviolet C (UVC)—100-280 nm Optical radiation comprises ultraviolet, visible, and infrared • Ultraviolet B (UVB)—280-315 nm radiation, which have wavelengths between 100 nm and 1 mm. • Ultraviolet A (UVA)—315-400 nm Their harmful effects are largely restricted to the skin and the • Visible—400-760 nm eye. Ultraviolet radiation is implicated in non-melanoma and • Infrared—760 nmϪ1 mm melanoma cancers. Outdoor workers—for example, farmers and the deck crews of ships—have an increased risk of The most potent sources of optical radiation non-melanoma cancer. Fortunately this is usually curable. As a are those in which the light waves are sensible precaution, all those who work outdoors should avoid coherent or in phase, typically coming from overexposure of the bare skin to sunlight and sunburn in order laser sources to reduce their risk of melanoma cancer. Some evidence suggests that exposure to ultraviolet radiation can impair the Working at pressure function of the immune system. • Atmospheric pressure is 14.7 psi • 1 atmosphere, 1 bar, 10 m (or 33 feet) of sea water, are broadly Ultraviolet radiation is responsible for the painful symptoms of arc eye (photokeratoconjunctivitis), which occurs some equivalent pressures hours after exposure to a bright source of ultraviolet radiation such as a welding arc. Often, bystanders who are adventitiously • Absolute pressure is that of the working environment added to exposed get this condition. atmospheric pressure Infrared radiation can cause thermal damage to the skin and eyes, both of which are easily protected, the latter with • Decompression illness is very rare at pressures below 1.7 bar appropriate goggles. In developed countries occupational cataract from exposure to infrared radiation is largely of absolute. There is no risk from slight elevations of pressure such historical interest, given proper protection. In developing as in clean rooms countries, however, cataracts may occur as a result of overexposure to infrared radiation, possibly exacerbated by • Typical pressures experienced in civil engineering works are in episodes of dehydration. the range 2-3.5 bar absolute Sources of optical radiation where the light waves are in phase (for example, from lasers) can cause serious thermal • Saturation diving techniques become necessary at depths below damage to the retina, and skin burns. Engineering and administrative controls and personal protection are needed to 50 m, 6 bar absolute prevent damage where high powered lasers are in use. Routine eye examination is not appropriate for laser workers, although a baseline assessment of visual acuity is useful to identify the functionally monocular individual, for whom a greater duty of care exists. If unusual skin symptoms are reported in workers exposed to optical radiation the possibility of photosensitisation should be considered, as can occur with exposure to plant products— for example, psoralens released in parsley cutting. Photosensitisation can also occur from certain drugs. If workers complain of “sunburn” from working in the vicinity of ultraviolet sources such as insect killing lamps, it is important to check that the bulbs have the correct frequency spectrum. Altered ambient pressure Compressed air is used in civil engineering to stabilise the ground and to remove water from workings. Alternative methods of doing so are available, and should always be considered before opting to use compressed air. The effects of hyperbaric exposure in diving and compressed air work are different. Surface diving usually entails short exposures to high pressures, whereas compressed air work generally entails 62

Physical agents prolonged exposures at relatively low pressures. In diving, the physical effort required for the task may be limited, often using only the arms, whereas heavy manual work may be undertaken in compressed air work. One effect that differs little in either situation is barotrauma—damage to an air containing organ by pressure exerted across a structure, typically in the ear or respiratory tract. Individuals exposed to raised pressures must be able to equalise such pressures—for example, by steady exhalation, during ascent from diving. The risk of barotrauma is minimised by excluding individuals with upper respiratory tract infections and by careful control of the rate of change of pressure during compression and decompression. Decompression illness and osteonecrosis Deep sea diver More serious health effects are decompression illness and osteonecrosis. Under pressure, inert gas (principally nitrogen) Decompression chamber dissolves in the tissues. When the pressure is reduced, this gas will come out of solution and form bubbles, in much the same Guidance on exposures, and international standards way that bubbles form when pressure on carbonated drinks is • ICNIRP. Guidelines for limiting exposure to time-varying released. These bubbles in turn cause effects which, if they are in the circulation or central nervous system, can be life electric, magnetic, and electromagnetic fields (up to 300 GHz). threatening. Health Phys 1998;74:494-522 Decompression illness occurs in two types: pain only • ICRP. 1990 Recommendations of the international commission on (previously type 1), in which symptoms occur in the skin (niggles) or around joints (bends), and serious (previously radiological protection. Annals of the ICRP 21,1-3. Oxford: type 2), in which symptoms can occur in the circulation or Pergamon Press, 1991 nervous system. Symptoms can arise from gas bubbles in the pulmonary or coronary circulations (for example, the chokes), • International Standards Organisation. Hot environments— or from damage to the brain or spinal cord (for example, the staggers). Serious decompression illness can be life threatening. estimation of the heat stress on working man, based on the WBGT index (wet bulb globe temperature). Geneva: ISO, 1989 (ISO 7243) To reduce the potential for bubble formation during decompression, pressure is reduced in a controlled, staged • International Standards Organisation. Moderate thermal manner, the details of which depend on the duration and pressure of the preceding hyperbaric exposure. At its simplest environments—determination of the PMV and PPD indices and this can be achieved by a series of timed stops at specified specification of the conditions for thermal comfort. Geneva: ISO, depths during ascent to the surface. 1993 (ISO 7730) Decompression regimens inevitably entail a compromise • International Standards Organisation. Ergonomics of the thermal between the long times needed for nitrogen to evolve from the tissues and the practical constraints arising from keeping a environment—Medical supervision of individuals exposed to extreme hot group of workers (in the case of civil engineering work) in the or cold thermal environments. Geneva: ISO, 2001 (ISO 12894) decompression chamber for long periods. The decompression chamber is an airlock between the working chamber and the external environment. Workers remain seated, resting, while the ambient pressure is reduced in a controlled fashion over one or more hours. Breathing oxygen during decompression helps to remove nitrogen from the body and shortens decompression times. As exposures increase in terms of both depth and time, longer decompression periods are required. At some of the higher pressures encountered in diving, the only practical approach is to adopt saturation methods, where individuals live and work under pressure for long periods, avoiding the need to decompress between working exposures. With careful control of decompression and oxygen breathing, the incidence of decompression illness in offshore diving work has been kept very low. Further advances are needed in civil engineering work, where oxygen decompression is not yet always routine. When decompression illness occurs it should always be treated by therapeutic recompression, as such events increase the risk of osteonecrosis. This serious complication of hyperbaric work results from compromise of the blood flow within bone structures. A section of normal bone dies and is replaced by softer material. If this occurs below the surface of a joint, such as the hip joint, there is a real risk of the joint surface collapsing, resulting in permanent disability. 63

ABC of Occupational and Environmental Medicine Risk factors for osteonecrosis are not clearly established. It can Further reading occur after one “bad” decompression but is normally seen only after higher pressure exposures. Risk factors in compressed air • Ashcroft F. Life at the extremes. London: Flamingo, 2001. work include the number of hyperbaric exposures and the number of episodes of decompression illness. A journalistic account by a professor of physiology of the science of survival, including chapters on altitude, diving, heat, and cold Barotrauma and decompression illness may occur in aviation environments. They are most likely to occur if an • Case RM, Waterhouse JM. Human physiology: age, stress and the aircraft pressurisation system fails at an altitude above 20 000 feet, after a high altitude ejection, or after flight at environment. Oxford: Oxford University Press, 1994. An altitude in an unpressurised aircraft. The risks can be undergraduate textbook with a series of short chapters on topics including minimised by breathing 100% oxygen (denitrogenation) the thermal environment, altitude, diving, and acceleration. Useful before flights or training exposures in an altitude chamber academic introduction to the areas covered carrying a risk of decompression illness. Osteonecrosis after decompression in aviation is exceedingly rare. • Edholm OG, Weiner JS. The principles and practice of human Living and working at altitude physiology. London: Academic Press, 1981. A bit dated, but still a Living and working at altitude carries different risks—namely, valuable reference on the physiology of diving, altitude, the thermal acute mountain sickness, high altitude pulmonary oedema environment, and other topics. Covers the basics in much more detail (HAPE), and high altitude cerebral oedema (HACE). than Case and Waterhouse Symptoms of acute mountain sickness can occur at altitudes of 2500 m, with the prevalence reaching 40% at altitudes over • Bennett PB, Elliott DH. The physiology and medicine of diving, 4000 m. The symptoms include headache, nausea and vomiting, sleep disturbance, and muscle weakness, and are thought to 4th ed. London: WB Saunders, 1993. A comprehensive textbook, arise from a mild oedema of the lungs, the splanchnic which includes a chapter on compressed air work. A standard reference circulation, and the brain. The condition is treated by descent covering all aspects of hyperbaric exposures including clinical hyperbaric to a lower altitude. Breathing oxygen, and taking acetazolamide oxygen therapy and dexamethasone can also help. The main preventive measure is to limit the rate of ascent to altitude. Unlike acute • Cummin AR, Nicholson AN. Aviation medicine and the airline mountain sickness, both high altitude pulmonary oedema and high altitude cerebral oedema are life threatening. The former passenger. London: Arnold, 2002. A multiauthored text considering is treated by descent and the use of oxygen. the aeromedical implications of a range of common medical conditions People who live at high altitude show physiological • Ernsting J, Nicholson AN, Rainford DJ. Aviation medicine, 3rd ed. adaptations to their environment, although even these may fail with time. Chronic mountain sickness (Monge’s disease) is a London: Butterworths, 2000. A comprehensive text covering all aspects loss of tolerance to hypoxia, which occurs particularly in of aviation physiology, psychology, and clinical aviation medicine; middle aged men. It results in an erythropoiesis, with the suitable for students of specialised aviation medicine diplomas haematocrit rising as high as 80%. Clinical effects include cyanosis, dyspnoea, cough, palpitations, and headache. • Harding RM, Mills FJ. Aviation medicine, 3rd ed. London: BMJ The condition can only be alleviated by moving to a lower altitude. Publishing Group, 1993. An introductory text for the general reader which gives a good overview of the main topics relevant to clinical Acceleration practice Exposure to sustained acceleration is experienced on • Mettler FA, Upton AC. Medical effects of ionising radiation, fairground rides (2-3 G) or in flight, and then only significantly in aerobatic or military flying. Radial acceleration occurs 2nd ed. Philadelphia: WB Saunders, 1995. A comprehensive and during banked turns. When the head is to the inside of the well referenced review of the science underlying the medical effects of turn the acceleration is positive in the “z” axis. With the head ionising radiation. Covers direct effects and carcinogenesis at length on the outside of the turn the acceleration is negative in the same axis. Positive G increases the hydrostatic weight of the • National Radiation Protection Board. Living with radiation. column of blood above the heart, reducing arterial pressure and perfusion of the retina and the brain. Negative G has the London: NRPB and HMSO, 1998. A book written for the lay reader opposite effect, increasing arterial pressure and resulting in which sets out a good introduction to the science and social context of engorgement of the head and neck exposures to both ionising and non-ionising radiations Protection from positive G is provided by posture, keeping • Parsons K. Human thermal environments, 2nd ed. London: the body nearer the horizontal plane than the vertical, by lifting the legs up and lowering the backrest. Valsalva type Taylor and Francis, 2002. A standard text on responses to hot, manoeuvres are used slightly in anticipation of acceleration to moderate, and cold thermal environments, presented as an integrated increase the pressure in the arterial system, and protective approach incorporating physiology, psychology, and environmental anti-G suits are routinely worn by military pilots. These prevent physics pooling of blood in the peripheries and limit the descent of the heart and diaphragm under acceleration • Report of the Advisory Group on Non-ionising Radiation. ELF Electromagnetic fields and the risk of cancer. London: NRPB 2001;Doc12:3-179. Scientific report covering exposures to electromagnetic fields, studies on cancer induction, epidemiological studies, and occupational exposures. Includes recommendations for further research • Stewart W. Mobile phones and health. Chilton Independent Expert Group on Mobile Phones, 2000. Report of a Government appointed review group with good coverage of mobile phone technology and the scientific evidence for health effects. Makes numerous recommendations for action • Ward MP, Milledge JS, West JB. High altitude medicine and physiology, 3rd ed. London: Arnold, 2000. A comprehensive review covering history, physiology, biochemistry, and the clinical effects of altitude and cold • Barry PW, Pollard AJ. Altitude illness. BMJ 2003;326:915–9. A well-referenced up-to-date clinical review Effects of positive headwards acceleration • 3-4 G—darkening of visual fields • 3.5-4.5 G—loss of peripheral vision • 5-6 G—loss of consciousness If the rate of onset of acceleration is high, loss of consciousness will be the first symptom 64

12 Noise and vibration Paul Litchfield Sound is generated when a vibrating source transmits energy to Relative response (dB) +10 the surrounding air, creating small changes in pressure. If the frequency of the sound produced lies between about 20 and 0 16 000 Hz it may be perceived by the hearing mechanism and is classed as being “audible.” Sound levels are measured in –10 decibels (dB), a logarithmic unit in which the faintest sound A detectable by the human ear is set at 0 and the level doubles B for every 3 dB. In assessing audible sound it is conventional to use a weighted scale that filters the actual pressure level in –20 specified octave bands by an agreed amount to resemble the C response of the ear over those frequencies. The most commonly used weighting is the “A” network, and resultant –30 units are expressed as dB(A). Noise is simply unwanted sound. –40 125 250 500 1000 2000 4000 8000 The body is also susceptible to non-acoustic vibration 63 Frequency (Hz) transmitted by direct contact with oscillating surfaces. As with sound, frequency is important: vibration below 2 Hz and above The human ear is more sensitive to certain frequencies, and in order to 1500 Hz is not thought to be harmful; motion between 5 Hz approximate the response of the ear it is possible to suppress certain and 20 Hz is considered potentially most damaging. Vibration frequencies and boost others in the electronic circuitry of sound level can be measured in various ways, but is normally expressed as meters. This technique is known as “weighting,” and the most commonly acceleration in metres per second squared (m/s2) averaged quoted weighting network is the A weighting over the three axes. As vibration at frequencies below 2 Hz and above 1500 Hz is not thought to cause damage, weighting is applied to measurements of vibration magnitude to allow for this frequency dependence of the risk of harm. Health effects of noise The principal hazard from noise is impairment of hearing. This may be confined to a reversible alteration in hearing levels, known as temporary threshold shift, which resolves spontaneously in the quiet. It may last from a few minutes to months depending on the noise level encountered. If exposure to high noise levels is sustained for a prolonged period a permanent shift can occur, termed noise induced hearing loss. Short bursts of very high intensity sound (such as an explosion or gunfire), known as impulse noise, can also cause additional harm to the ear by rupturing the tympanic membrane or even disrupting the ossicles. There has been considerable interest in recent years in the non-auditory effects of noise. Comprehensive literature reviews Non-auditory health and physiological effects of noise Vibration is usually measured in three orthogonal directions at the interfaces between the body and the vibrating surface • Cardiovascular effects: in laboratory studies, noise has been shown Range of instruments for measuring noise and vibration levels to produce increases in diastolic blood pressure. However, there is no clear evidence that long term exposure to noise is a risk factor for hypertension • Some studies suggested an association between noise exposure or noise annoyance and the frequency of psychiatric symptoms but these findings have been questioned in later studies. There is some evidence that noise sensitivity is an indicator of vulnerability to minor psychiatric disorder, and that annoyance responses are stronger among individuals with psychiatric disorders • The effect of noise on performance is complex. Some research found no clear evidence of effects at noise levels below 95 dB, whereas other research suggests that performance may be affected at much lower levels • Fatigue, headaches, and irritability have been found to be over-represented in groups exposed to noise, but methodological flaws in study design have made valid conclusions difficult 65

ABC of Occupational and Environmental Medicine have been published, but much of the evidence remains weak Audiogram showing noise induced hearing loss with classical depression at or equivocal. 4 kHz Noise induced hearing loss Noise induced hearing loss in the United Kingdom (adapted Noise induced hearing loss is caused by damage to the cilia on from Health and Safety Executive statistics 2000-1) the basilar membrane in the organ of Corti in the inner ear. This damage is progressive and irreversible and results in loss • UK Health and Safety Executive statistics are obtained from of both absolute sensitivity of the ear and in frequency a variety of sources, including the occupational physicians reporting selectivity. Characteristically, loss is initially predominant in the activities (OPRA), occupational surveillance scheme for audiologists higher frequencies (3-6 kHz) and classically, a depression at (OSSA), and industrial injuries scheme (prescribed diseases) 4 kHz may be seen on audiometry. With continuing exposure hearing loss extends to both higher and lower frequencies and • The industry groups with the highest annual average incidence rates is frequently superimposed on the effects of age related of new cases qualifying for benefit were extraction, energy, and water hearing loss, also known as presbyacusis. supply (7.9 cases per 100 000 employees), manufacturing (3.9), and construction (2.3) (based on 1999 and 2000 data). Of cases The development of noise induced hearing loss is insidious, qualifying for benefit, 11% were in shipbuilding, repair, or breaking, and deafness may be considerable by the time an individual and 9% were in the coal mining industry. Of new cases qualifying for seeks assistance. Initially those affected describe difficulty in benefit in 2000, 52% were in the occupational group of metal hearing conversations against a noisy background. Because machinery and related trades workers consonants have a higher frequency than vowels, they are more difficult for a person with noise deafness to recognise, with • Noise induced hearing loss is not reportable under the Reporting of resultant degradation of discrimination of speech. Hearing loss Injuries, Diseases and Dangerous Occurrence Regulations 1995 is frequently associated with tinnitus, which may be more (RIDDOR) disabling than deafness. On examination, the tympanic membranes usually seem normal, but testing with a tuning fork Number of cases shows a sensorineural deafness. Industrial noise usually gives (OSSA/OPRA, estimated for 2000) rise to bilateral hearing loss but specific activities, such as use of firearms, may produce unilateral deafness depending on the Sensorineural hearing loss 627 location of the noise source in relation to the ears. Audiometry Tinnitus 161 shows a hearing loss that is predominantly high frequency, Balance problems although in severe cases lower frequencies are affected. This Tympanic disorder 5 latter case produces far greater disability because of the impact Other problems 3 on the speech range (0.5-2.0 kHz). Total 1 Prescribed diseases* 797 (648 individuals) Noise induced hearing loss is common. Data from the UK 226 National Household Survey indicate that in excess of 130 000 people have hearing problems arising from noise at work, and *To qualify for benefit, there must be at least 50 dB of hearing loss. The the Occupational Safety and Health Administration estimates degree of disability is calculated from the hearing loss in such a way that there are 10 million people with similar hearing problems in that 50 dB in both ears equates to 20% disability. Under current the United States. Manufacturing industry has been the source guidelines, a worker must have been employed for at least 10 years in of most cases in the past, but noise levels can be high for those specified noisy occupations. Of the almost 2000 disallowed claims in working in many other sectors including construction, transport, 1998, 800 claimants had 35-49 dB hearing loss and the armed forces. More recently, concern has been raised in relation to call centre operatives, but any potential problems Differential diagnosis of noise induced hearing loss seem to relate to extraneous noises received through headsets (acoustic shock) rather than to ambient noise levels. • Conductive—Wax, acute otitis media, chronic otitis media, otosclerosis, tympanic membrane injury, barotrauma, ossicular Risk management dislocation Noise induced hearing loss is a preventable condition and, as with any hazard, the first step is to assess the risk. As a general • Sensorineural—Presbyacusis, congenital (maternal rubella, guide, noise levels are likely to be hazardous if communication hereditary, perinatal anoxia), infective (measles, mumps, without shouting is difficult at a distance of two metres. If there meningitis), vascular (haemorrhage, spasm or thrombosis of is reason to believe that there may be a problem then noise cochlear vessels), traumatic (head injury), toxic (streptomycin, levels should be measured by a competent person. The risk of neomycin, carbon monoxide, carbon disulphide), Meniere’s disease, developing noise induced hearing loss is a function of both the late otosclerosis, acoustic nerve tumours (usually unilateral) level of noise exposure and its duration. Noise levels are therefore often expressed as daily personal noise exposure (L EP,d), which averages the dose over an eight hour working day. L EP,d action levels of 85 dB(A) and 90 dB(A) have been set in both the United States and European Union, above which certain control measures are mandatory. However, at the time of writing, negotiations are far advanced in Europe for a new Noise Directive, which will replace the existing directive (86/188/EC, implemented in the United Kingdom by the Noise at Work Regulations 1989) with tougher legislation that will reduce the action levels to 80 dB(A) and 85 dB(A), and introduce a limit value on exposure of 87 dB(A). The best means of hazard control is elimination, and machinery noise can often be reduced substantially by better 66

Noise and vibration Main requirements of the UK Noise at Work Regulations 1989 Action required where L EP,d* is likely to be: Ͻ85 dB(A) 85 dB(A) 90 dB(A) √ First action Second action Empolyers’ duties level level† General duty to reduce risk √ √ √ Risk of hearing damage to be reduced to the lowest level reasonably √ practicable* √ √ √ √ Assessment of noise exposure √ √ √ • Noise assessments to be made by a competent person • Record of assessments to be kept until a new one is made √ √ √ Noise reduction √ Reduce exposure to noise as far as is reasonably practicable by √ √ means other than ear protectors √ √ √‡ Provision of information to workers √ • Provide adequate information, instruction, and training about √ risks to hearing, what employees should do to minimise risk, how they can obtain ear protectors (if they are exposed to an L EP,d between 85 and 90 dB(A)), and their obligations under the Regulations • Mark ear protection zones with safety signs, so far as reasonably practicable Ear protectors Ensure so far as is practicable that protectors are: • Provided to employees exposed to an L EP,d of 85 dB(A) or above and less than 90 dB(A), who ask for them • Provided to all exposed above the second action level • Maintained and repaired • Properly used by all exposed Ensure so far as reasonably practicable that all who go into a marked ear protection zone use ear protectors Maintenance and use of noise control equipment Ensure so far as is practicable that: • All equipment provided under the Regulations is used, except for the ear protectors provided between first action level and second action level Ensure all equipment is maintained Employees’ duties Use of equipment; so far as is practicable: √√ √ √√ √ • Use ear protectors √ • Use any other protective equipment • Report any defects discovered to employer Machine makers’ and suppliers’ duties Provision of information In theory if √ √ Provide information on the noise likely to be generated equipment provided to comply with* *The dB(A) action levels are values of daily personal noise exposure L EP,d. †All the actions indicated at 90 dB(A) are also required where the peak sound pressure is at or above 200 pascals. ‡This requirement applies to all who enter the zones, even if they do not stay long enough to receive an exposure of 90 dB(A) L EP,d. design and maintenance. Damping and enclosure of vibrating machinery can greatly reduce exposure, or people can be provided with well insulated noise refuges in otherwise noisy environments. As a last resort, people can be issued with hearing protection: ear muffs (which completely cover the ear), ear plugs (which are inserted into the auditory canal), or semi-inserts (which cover the entrance to the ear canal). It is important to ensure not only that any ear protection offered provides adequate noise attenuation but also that it does not interfere with any other protective equipment required, and that those using it understand that even short periods of non-use will greatly reduce the protective value. Health surveillance Noise hazard sign to indicate that use of hearing protection is mandatory Health surveillance (including audiometry), although not and standard design of ear muffs a legal requirement, can provide a useful adjunct to risk management and is considered good practice where the second action level (see table) is exceeded. Hearing conservation 67

ABC of Occupational and Environmental Medicine programmes will normally include a structured interview to Classification of audiograms into warning and referral gather relevant health data. This should cover relevant medical levels history based on the differential diagnosis for noise induced hearing loss, and a history of previous noise exposure such as Sum of hearing levels previous employment in noisy industries, service in the armed forces, and leisure pursuits such as shooting or regular clubbing. 0.5, 1, 2 kHz 3, 4, 6 kHz The ear canal and tympanic membrane should be examined. Personal protective equipment should be inspected, and Age in Warning Referral Warning Referral workers reminded of its correct use. Audiometric testing should years level level level level be undertaken in a soundproof booth, and the screening results 20-24 45 60 45 should be fully discussed, with onward referral if required. 25-29 45 66 45 75 30-34 45 72 45 87 Such programmes aim to identify at an early stage 35-39 99 individuals particularly susceptible to noise damage, and to 40-44 reinforce hazard information together with the use of control 45-49 48 78 54 111 measures. The UK Health and Safety Executive has produced 50-54 comprehensive guidelines on the conduct of audiometric 55-59 51 84 60 123 testing programmes, including a helpful categorisation scheme 60-64 that provides a template for the management of individuals 65 54 90 66 135 according to the degree of hearing loss identified. The five categories within the scheme and the suggested action for each, 57 90 75 144 and a chart of age related hearing loss at low and high frequencies are given in the two tables. 60 90 87 144 65 90 100 144 70 90 115 144 The Health and Safety Executive categorisation scheme Category Symptom Suggested action 1 Referral Rapid change in hearing threshold has occurred (that is, a change 2 in the sum of the hearing levels for either the low or high Referral frequencies of 30 dB, compared with the previous audiogram, or 3 45 dB if the period between the tests is more than three Referral 4 years). This change may be due to noise exposure or disease Warning. Formally notify the employee of the This is usually related to medical factors. Unilateral hearing presence of hearing damage. Employee to loss is not normally noise induced and may indicate auditory understand that they have suffered some nerve disease. Unilateral hearing loss is considered to exist if hearing loss; it is essential that they the difference in the sums of the hearing levels between the comply with the employer’s hearing two ears exceeds 45 dB for the low frequencies, or 60 dB for conservation measures. Assess rate of progression the high frequencies of hearing loss None, but assess rate of progression Results show a pattern that could suggest significant noise of hearing loss inducing hearing loss (that is, where the sum of either the low or high frequencies, or both, in either ear, exceeds the value given for the appropriate age band) Hearing has deteriorated beyond the level that might be accounted for by age alone, but not to the extent that medical referral is required 5 Within normal limits Health effects of vibration Vibration and noise often emanate from the same source. Vibration may reach the body through a number of pathways, but consideration of adverse health effects centres on whole body vibration and hand arm vibration. As with noise, the risk of harm is a function of both the magnitude of exposure and of its duration: “doses” are therefore adjusted to a standard reference period of eight hours to allow comparison, and this figure is termed A(8). Measuring vibration is complex and should only be undertaken by those with specialist training. Whole body vibration Use of a vibrating tool for road breaking Interest in the effects of whole body vibration stems from the middle of the 20th century when mechanisation, particularly of transport, became more prevalent. Vibration is transmitted either from a machine platform through the feet, or from a 68

Noise and vibration seat through the buttocks. Exposure is most likely to occur with Vibration induced disorders in the United Kingdom vehicle use and this includes road, off road, rail, air, and maritime use: it is estimated that as many as 9 million people in • A UK survey on behalf of the Health and Safety Executive gave the United Kingdom are regularly exposed to whole body vibration. The disorders reported in groups exposed in this way an estimate for the national prevalence estimate of vibration include gastric problems, vestibular dysfunction, circulatory changes, menstrual disturbance, and psychological effects. white finger (VWF) of 288 000 However, the main problem associated with whole body vibration is back pain, and the UK Health and Safety Executive • The industry with the highest annual average rate of new estimates that up to 21 000 cases may be caused by exposure, with a further 13 500-31 500 cases of exacerbation of a assessments of disability at 1% in 1999-2000 was extraction, pre-existing condition. The evidence base for a causal link between whole body vibration and back pain nevertheless energy, and water supply, because of the relatively high number remains weak, and has recently been comprehensively reviewed. of claims made by current or former coal miners. Of the new Hand arm vibration assessments made in other industries, 3% were in shipbuilding, Vibration may be transmitted to the hands and arms by the use of hand held power tools, hand guided machinery, or by repair, or breaking; 5% were in other manufacturing industry; holding materials being processed by machines. Exposure is particularly common in agriculture, construction (particularly and 4% in construction scabbling), mining, engineering, forestry, public utilities, and shipbuilding. It is estimated that about 1 million people in the • In 1999-2000, coal mining accounted for 46% of cases for carpal United Kingdom are exposed to potentially harmful levels of hand arm vibration in their work, and as many as 300 000 may tunnel syndrome, construction for 12%, and shipbuilding, have developed adverse health effects as a result. repair, or breaking for 4% The health effects of exposure to hand arm vibration have been recognised for many years and have been ascribed a variety No of cases* of labels. There is now general consensus on the use of the term “hand arm vibration syndrome” to describe the vascular Raynaud’s phenomenon or hand arm 935 (sometimes also known as vibration white finger), neurological, vibration or vibration white finger and musculoskeletal symptoms that can result. Acute vibration exposure causes vasoconstriction of the blood vessels supplying RIDDOR† (2000-1 provisional) 119 the fingers and, if prolonged, it may damage the endothelium Carpal tunnel syndrome 905 and stimulate smooth muscle proliferation so that the lumen of Hand arm vibration the vessels gradually narrows. Damage also occurs to the peripheral nerves, with acute oedema and chronic demyelination. Prescribed diseases (1999-2000) 3212 Muscular weakness in the hand is common, carpal tunnel Vibration white finger 475 syndrome is recognised in some cases, and there is evidence to Carpal tunnel syndrome indicate that premature osteoarthrosis of the wrist and elbow may occur. The precise relation between these elements of the *Musculoskeletal occupational surveillance scheme (MOSS), syndrome remains a matter for debate, but there is no doubt that reporting by rheumatologists or occupational physicians reporting the vascular and neurological components can occur separately. activities (OPRA), estimated for 2000. †RIDDOR, Reporting of Injuries, Diseases and Dangerous In the early stages of vibration injury the only symptom may Occurrence Regulations 1995 (adapted from Health and Safety be a tingling in the fingers, most noticeable at the end of the Executive statistics 2000-1). working day. This may be associated with a loss of sensation and periodic blanching of the tips of the fingers when exposed to Differential diagnosis cold. As the condition progresses the blanching extends to the root of the fingers, although the thumbs are rarely affected. In Vascular conditions more severe cases there is considerable pain, with a loss of grip strength and dexterity, and attacks may occur even in warm • Connective tissue disease—scleroderma, mixed connective tissue surroundings. Rarely the condition can progress to the extent that circulation is permanently impaired and the fingers disease, systemic lupus erythematosus, rheumatoid arthritis, become cyanosed—exceptionally, cases of vibration induced gangrene have been reported. dermatomyositis, polyarteritis nodosa, Sjogren’s disease Risk management • Traumatic—after injury or surgery, hand transmitted vibration, Assessment of risk is based on the type of vibrating equipment employed and its pattern of use. In the United Kingdom the frostbite, thoracic outlet syndrome action level for introducing preventative measures is if exposure regularly exceeds an A(8) of 2.8 m/s2 (dominant • Arterial disease—thromboangitis obliterans, thromboembolism, axis). It is important to recognise that this is not a “safe” level: some individuals are likely to develop hand arm vibrations with arteriosclerosis prolonged use even if this threshold is not exceeded. A new European Vibration Directive has recently been adapted • Toxins and drugs—vinyl chloride, ergot, ␤ blockers, clonidine (to be transferred into UK law in 2005), which sets a limit value • Dysglobulinaemia—cryoglobulinaemia • Neurogenic—poliomyelitis, syringomyelia, hemiplegia Neurological conditions • Peripheral nerve entrapment—carpal tunnel syndrome, ulnar nerve entrapment at elbow or wrist, thoracic outlet syndrome • Central nervous system disorders—compression myelopathy (spondylosis or spinal cord tumor), subacute combined degeneration of the cord, multiple sclerosis • Peripheral neuropathy—diabetic, alcoholic, toxic (for example, organophosphates, thallium, acrylamide, carbon disulphide, n-hexane, methyl butyl ketone, diethyl thiocarbamate, lead) • Drug induced (for example, chloramphenicol, isoniazid, streptomycin, polymyxin, ethambutol, nitrofurantoin, metronidazole, gold, indomethacin, vincristine, perhexiline, phenytoin) 69

ABC of Occupational and Environmental Medicine on exposure of 5 m/s2 (sum of three axes) and an action value Vibration induced gangrene of 2.5 m/s2 (sum of three axes). Stockholm workshop classification Manufacturers of vibrating tools may be able to provide useful data on levels under standard conditions, but care must Vascular component be taken because actual levels in field use can differ substantially from those generated in a controlled environment. Stage Grade Description Similarly, field measurements can vary widely depending on 0 mode of use and the materials being worked. In practice it is 1V Mild No attacks therefore usual to institute a preventive programme wherever 2V there is prolonged use of tools likely to be hazardous. Occasional attacks affecting only the 3V tips of one or more fingers Prevention programmes aim to eliminate or substitute the 4V hazardous process where possible. Where this is not possible, Moderate Occasional attacks affecting distal the procurement of low vibration machinery, fitting of vibration and middle (rarely also proximal) reducing adaptations (such as vibration reducing handles), phalanges of one or more fingers regular maintenance and re-engineering of processes to avoid the need for prolonged tight gripping of high vibration parts Severe Frequent attacks affecting all will reduce exposure. Keeping the hands and body warm helps phalanges of most fingers to maintain a good blood supply to the fingers and thereby reduces the risk of injury. Vibration reducing gloves are Very severe As in stage 3 with trophic changes in available but their efficacy is limited. A key element in the fingertips a preventive programme is the provision of training and information about the hazard and the means of Stage Sensorineural component reducing risk. 0SN 1SN Description Health surveillance 2SN Health surveillance aims to identify those who develop early Vibration-exposed but no symptoms symptoms so that progression can be avoided and it is 3SN Intermittent numbness with or without tingling appropriate if exposure levels are likely to trigger a prevention Intermittent or persistent numbness, reduced programme. Pre-employment screening is helpful in identifying sensory perception individuals with conditions such as Raynaud’s disease that are a Intermittent or persistent numbness, reduced tactile contraindication to work with vibrating tools, in establishing discrimination or manipulative dexterity or both baseline measurements, and in educating workers about measures to minimise risk—not least the avoidance of smoking. ˚C 40 Test parameters: It is good practice to repeat the assessment for newly exposed Period of Settling time = 2.0 minutes workers to identify those who may be particularly susceptible. Provocation time = 5.0 minutes Thereafter, annual review is recommended, with any provocation Recovery time = 11.0 minutes symptoms being reported to a designated person as soon 35 Provocation + 15˚C water bath as they occur. 30 Test site 1 = left index Assessment should comprise a structured history and Test site 2 = left middle relevant clinical examination that will identify early hand arm 25 Test site 3 = left ring vibration syndrome and assist with differential diagnosis, as Test site 4 = left little a number of constitutional conditions give rise to similar Test site 5 = right index symptoms. Guidelines from the UK Health and Safety Executive Test site 6 = right middle (see Further reading) give a sample questionnaire and Test site 7 = right ring guidance on tests that may be helpful for examination. Various Test site 8 = right little methods of grading signs and symptoms have been devised and those of Taylor and Pelmear, and Griffin have been widely 20 used. However, the most commonly used system of classification for hand arm vibration syndrome is currently the Stockholm 15 0 5 10 15 20 Workshop scale, which grades the vascular and sensorineural Minutes components by severity. This scale, and the speed of progression along it, can helpfully be used to guide the Results of cold provocation showing an abnormal response as found in management of affected workers. No effective treatment is vascular damage from hand arm vibration syndrome available for this condition: management relies on adjustments to work, and limitation of vibration exposure. Cessation of vibration exposure may well compromise an individual’s continuing employment, and great care is therefore required before making any such recommendation. A number of additional test measurements (detailed Lindsell CJ and Griffin MJ, 1988) can be carried out by specialist centres to help confirm the degree of incapacity, and referral should be considered in such circumstances. The photographs showing the range of instruments for measuring noise and vibration and showing a vibrating tool for road breaking are courtesy of Castle Instruments. The figure showing how vibration is measured is adapted from HS(G)88. 70

Noise and vibration Further reading and Griffin define a standardised battery of tests for detecting the various • Butler MP, Graveling RA, Pilkington A, Boyle AL. Non-auditory components of hand arm vibration syndrome effects of noise at work: A critical review of the literature post 1988. HSE • Faculty of Occupational Medicine of the Royal College of Contract Research Report 241/1999. Sudbury: HSE Books, 1999. A Physicians of London. Hand-transmitted vibration: clinical effects review of the literature relating to the non-auditory effects of noise since and pathophysiology. London: Faculty of Occupational Medicine of the Royal College of Physicians of London, 1993. Part one 1988, updating earlier work by Smith and Broadbent, considering summarises the evidence relating to hand arm vibration syndrome and behavioural and psychological elements as well as physiology and health recommends assessment methodologies; part two outlines in some detail • Health and Safety Executive. A guide to audiometric testing the evidence base for the report. Currently being revised; publication is programmes. Guidance Note MS 26. Sudbury: HSE Books, 1995. planned for 2004 Practical guidance on the conduct of occupational audiometry • OHSA. Noise and Hearing Conservation. Occupational Safety and • Stayner RM. Whole body vibration and shock: A literature review. Health Administration. US Department of Labor. Revised 15 Sudbury: HSE Books, 2001. (HSE Contract Research Report February 2002. http://www.osha-slc.gov/SLTC/ 333/2001) Review of the effects of whole body vibration, comparing the noisehearingconservation/. The OSHA site provides links to a wide state of knowledge with noise induced hearing loss and hand transmitted range of US Government documents relating to noise and hearing vibration; concentrates on the relationship with low back pain conservation • Health and Safety Executive. Hand-arm vibration. HS(G)88. • Palmer KT, Coggon D, Griffith MJ, Haward BM. Hand-transmitted Sudbury: HSE Books, 1994. Practical guidance on the hazards, vibration: occupational exposure and their health effects in Great Britain. Sudbury: HSE Books, 1999 (HSE Contract Research assessment methods and controls for hand transmitted vibration Report 232/1999) • Lindsell CJ, Griffin MJ. Standardised diagnostic methods for assessing components of the hand-arm vibration syndrome. Sudbury: HSE Books, 1988 (HSE Contract Research Report 197/1988) Lindsell 71

13 Respiratory diseases Ira Madan The pattern of occupational lung disease is changing in Estimated number of cases of work related and industrialised countries. A reduction in manufacturing occupational respiratory disease reported to industries and stricter health and safety legislation during the SWORD/OPRA by diagnostic category, 1998-2000 past 50 years have resulted in a sharp decline in the incidence of silicosis, asbestosis, and other pneumoconioses. Asthma is Diagnostic category 1998 1999 2000 now the most common occupational respiratory disorder in these countries. By contrast, the traditional occupational lung Benign pleural disease 625 1243 1080 diseases are commonly seen in developing countries, and Asthma 807 1129 797 occupational asthma is reported less often. However, the true Malignant mesothelioma 701 1018 964 prevalence of asthma attributable to occupation in these Pneumoconiosis 225 292 countries remains unknown. Other diagnosis 187 320 218 Inhalation accidents 178 239 119 Since 1989, the understanding of the epidemiology of Bronchitis/emphysema 154 144 occupational lung disease in the United Kingdom has been Lung cancer 58 126 greatly enhanced by the Surveillance of Work related and Infectious disease 112 29 77 Occupational Respiratory Disease (SWORD) and Occupational Allergic alveolitis 81 37 Physicians Reporting Activity (OPRA) projects. Occupational Total number of diagnoses 87 63 and respiratory physicians systematically report new cases of Total number of individuals* 29 42 3854 occupational lung diseases, together with the suspected agent, 3009 4418 3787 industry, and occupation. The projects have provided an 2934 4298 estimate of the incidence and pattern of occupational lung disease in the United Kingdom. *Individuals may have more than one diagnosis. Occupational asthma Glues Solder/ and colophony Occupational asthma is a disease characterised by variable resin airflow limitation and airway hyper-responsiveness caused by Laboratory specific agents inhaled in the workplace. It does not include animal and 5% Isocyanates activation of pre-existing asthma or airway hyper-responsiveness 6% induced by non-toxic irritants or physical stimuli such as cold air. insects 7% Two types of occupational asthma are recognised: 29% immunological asthma appears after a latent period of occupational exposure; non-immunological occupational Wood dust 11% asthma develops without a period of latency and is associated with exposure to high concentrations of irritants. This latter 13% 9% type is referred to as reactive airways disease and is discussed 20% Latex separately. To date, more than 250 agents capable of causing immunological occupational asthma have been reported. In Gluteraldehyde some jobs, such as hairdressing and farming, workers are exposed to many potential sensitisers and sensitisation may Flour and grain occur through interaction of several agents. Top eight suspected causative agents for occupational asthma cases reported Substances that induce occupational asthma are classified as to SWORD/OPRA 1998-2000 either high (Ͼ5 kDa) or low molecular weight allergens. High molecular weight substances are usually protein derived Farmers are at particular risk of developing occupational asthma because allergens such as natural rubber latex and flour. It is thought they are often exposed simultaneously to an array of potential sensitisers, that some low molecular weight chemicals, such as such as animal derived allergens, arthropods, moulds, plants, and fungicides diisocyanates, act as haptens and combine with a body protein to form a complete antigen. Atopic individuals seem to be at increased risk of developing occupational asthma from some agents that induce specific immunoglobulin E (IgE)—for example, rat urinary proteins, and protease enzymes derived from Bacillus subtilis (detergent workers). However, atopic workers who are exposed to other agents—for example, isocyanates and plicatic acid (Western red cedar) seem to be at no more risk than non- atopic workers. Tobacco smokers are at greater risk of developing asthma after occupational exposure to several agents such as platinum salts, acid anhydride, and green coffee bean; the mechanism of this modifying effect is unknown. 72

Respiratory diseases Tobacco smoking and atopy are common among the working Examples of high and low molecular weight substances that population. If these risk factors are found at pre-employment may cause occupational asthma assessment the individual should not automatically be excluded from working with a respiratory sensitiser Chemicals (low molecular weight) Occupational group at Toluene di-isocyanate risk/industrial use Diagnosis Colophony (pine resin) Car or coach paint spray Between 5% and 10% of adult asthma is attributable to Complex platinum salts Electronics industry occupational factors. A detailed history of past and present Platinum refinery workers occupational exposures is therefore essential in the assessment Proteins (high molecular weight) of a patient with adult onset asthma. Coughing at work or at Flour or grain Bakers the end of a shift is often the first symptom and precedes Rodent urinary proteins Laboratory workers wheezing. Concurrent nasal congestion, lacrimation, and Salmon proteins Fish processing plant workers conjunctivitis may be associated with exposure to high Natural rubber latex Healthcare professionals molecular weight substances. The symptoms generally improve at weekends and holidays, but at advanced stages the Peak expiratory flow (l/min) 500 respiratory symptoms may persist. Where possible, advice should be sought from the patient’s employer’s occupational 400 health service, as they will have information on the substances that the employee is exposed to and will know if other workers 300 have developed similar respiratory symptoms. 200 Investigations Sun Mon Tue Wed Thu Fri Sat Sun Mon Tue Wed Thu Fri Sat Sun Patients should record the best of three measurements of peak expiratory flow made every two hours from waking to Work Home Work Home sleeping over a period of one month (charts are available from Clement Clarke International Limited). Ideally, this period Days of week should include one or two weeks away from work. A drop in peak expiratory flow or substantial diurnal variability on Self recorded peak expiratory flow measurements showing a classic pattern working days but not on days away from work supports a of occupational asthma diagnosis of occupational asthma. If there is any doubt, the patient should be referred to a specialist centre for further Specialist investigation of occupational asthma investigation. (a) Identification of atopy: skin prick tests with common A bronchial provocation test (inhalation test) with the allergens—for example, grass pollen, Dermatophagoides suspected agent may be required to give the patient advice pteronyssinus, and cat fur about future employment. The test may precipitate severe bronchospasm, so the procedure must be undertaken in a (b) Skin prick tests with specific extracts of putative sensitising specialist hospital unit with inpatient facilities. The individual is agent exposed to the suspected sensitiser in circumstances that most closely resemble their exposure at work. Forced expiratory (c) Serology: radioallergosorbent tests (RAST) to identify specific volume in one second (FEV1), forced vital capacity, and IgE antibody responsiveness to histamine or methacholine are measured serially and then compared with serial measurements taken (d) Bronchial provocation test with the suspected causative agent during a control challenge test performed on a separate day. An increase in airway hyper-responsiveness, particularly a late A worker who develops occupational asthma response, caused by the putative agent in concentrations that should avoid further exposure to the occur at work is taken as evidence of an allergic response. causative agent. As this often means Although bronchial provocation testing is considered the relocation or loss of current employment, it is gold standard test for the diagnosis of occupational asthma, essential that the specific cause is identified false negatives can arise if the testing is conducted with the accurately wrong material or if the concentration of the suspected agent is too low. Management Treatment of acute occupational asthma is the same as for asthma generally, but it is important to remove the sensitised individual from exposure to the substance causing their asthma, as subsequent exposure to even minimal quantities of the sensitising agent may precipitate severe bronchospasm. If their job entails working with the causative agent, relocation to another area will need to be considered. The employer’s occupational physician will be able to advise on suitable areas for redeployment and will be in a position to liaise with the employee’s manager. The employer should review their statutory risk assessments and control measures in the area 73

ABC of Occupational and Environmental Medicine where the affected employee was working to prevent other Diagnostic criteria for reactive airways disease syndrome workers being similarly affected. • History of inhalation of gas, fume, or vapour with irritant Reactive airways disease properties Exposure to gases • Rapid onset of asthma like symptoms after exposure Although fatalities from exposure to gases in the workplace are • Bronchial hyper-responsiveness on methcholine challenge test now rare in industrialised countries, inhalation accidents still • Individual previously free from respiratory symptoms occur relatively often. Accidental inhalation of gas (most commonly chlorine), fume, or vapour with irritant properties The Bhopal disaster in India highlighted the need for can lead to reactive airways disease. Frequently, individuals rapid access to expert advice in the event of a chemical complain of a burning sensation in their nose and throat within disaster minutes of exposure. The symptoms of asthma develop within 24 hours. The airway irritability usually resolves spontaneously but can persist indefinitely, and it may be provoked by a range of irritants or other provoking factors—for example, cold. The key to preventing the syndrome is good health and safety management. On a wider scale, industrial accidents involving the release of a toxic irritant gas may cause pulmonary injury or even death in the surrounding population. The release of methylisocyanate from the Union Carbide pesticide plant in Bhopal, India, in 1984 resulted in many deaths from acute pulmonary oedema. Survivors still have chronic respiratory ill health. Byssinosis Harvested cotton consists of leaves, bracts, stems, bacteria, fungi, and other contaminants. Steaming or washing it before processing can reduce the The symptoms of byssinosis occur as a result of hypersensitive biological activity of cotton airways and an acute reduction in FEV1 in susceptible individuals when they are exposed to dusts of cotton, sisal, hemp, or flax. It occurs most commonly in cotton mill workers and is probably a response to inhaled organic contaminants of the cotton boll, such as cotton bract (leaves at the base of the cotton flower that become hard and brittle during harvesting and comprise a major constituent of cotton dust in the mill). Smokers are at increased risk of developing the disease, but the pathogenic mechanisms underlying the disease remain obscure. Characteristically, individuals experience acute dyspnoea with cough and chest tightness on the first day of the working week, three to four hours after the start of a work shift. The symptoms improve on subsequent working days, despite continued exposure to the sensitising agent. As the disease progresses the symptoms recur on subsequent days of the week, and eventually even occur at weekends and during holidays. Exposure of textile workers to cotton and flax dust per se does not seem to cause a significant loss of lung function. However, if the subset of workers who develop byssinosis are not removed from further exposure, they go on to develop long term respiratory impairment and subsequently have an excess risk of mortality from respiratory disease. Pneumoconiosis Chest radiograph of quarry worker showing extensive simple silicosis Pneumoconiosis is the generic term for the inhalation of mineral dust and the resultant diffuse, usually fibrotic, reaction in the acinar part of the lung. The term excludes asthma, neoplasia, and emphysema. Silicosis is the commonest type of pneumoconiosis worldwide. It is caused by inhalation of crystalline silicon dioxide, and may affect people working in quarrying, mining, stone cutting and polishing, sandblasting, and fettling. Silicosis 74

Respiratory diseases occurs in several different forms depending on the level and Silicotic nodule duration of exposure. Classification of radiographs for pneumoconiosis is based on Simple nodular silicosis is the most common form, and is the 1980 International Labour Office (ILO) system. This is a similar clinically and radiographically to coal worker’s method of describing the pattern and severity of the change in pneumoconiosis. Chronic silicosis presents with increasing groups of workers. The classification has been used worldwide dyspnoea over several years and chest radiography shows upper for epidemiological research, surveillance, and medical checks lobe fibrosis or calcified nodules. Acute silicosis results from a of dust exposed workers brief but heavy exposure: patients become intensely breathless and may die within months. Chest radiographs show an appearance resembling pulmonary oedema. Accelerated silicosis occurs as the result of less heavy exposure and presents as slowly progressive dyspnoea caused by upper lobe fibrosis. Coal worker’s pneumoconiosis is caused by inhalation of coal dust, which is a complex mixture of coal, kaolin, mica, silica, and other minerals. Simple coal worker’s pneumoconiosis usually produces no symptoms or physical signs apart from exertional dyspnoea. The diagnosis is made by a history of exposure and the presence of characteristic opacities on chest radiographs. A small proportion of individuals with simple coal worker’s pneumoconiosis go on to develop progressive massive fibrosis which, when sufficiently advanced, causes dyspnoea, cor pulmonale, and ultimately death. Coal worker’s pneumoconiosis is disappearing in developed countries as mines close and working conditions improve; however, it remains widespread in China and India. Chronic obstructive pulmonary disease and mining The relationship between occupational exposure to coal dust and loss of ventilatory function is well established. However, after accounting for the effects of smoking and dust exposure, some miners still develop a severe decline in FEV1; the reasons for this are not fully understood. In the United Kingdom, chronic obstructive pulmonary disease due to coal dust is a prescribed industrial disease in those who have worked underground for at least 20 years and whose FEV1 is at least 1 litre below the predicted value. Asbestos related diseases Coal miners’ pneumoconiosis Exposure to asbestos causes several separate pleuropulmonary Occupational groups at greatest risk of developing asbestos disorders, including pleural plaques, diffuse thickening of the related diseases pleura, benign pleural effusions, asbestosis, bronchial cancer, • Carpenters and electricians and malignant mesothelioma. Bronchial cancer and malignant • Builders mesothelioma are discussed in chapter 15. • Gas fitters • Roofers Asbestosis is a diffuse interstitial pulmonary fibrosis caused • Demolition workers by exposure to fibres of asbestos, and its diagnosis is aided by • Shipyard and rail workers obtaining a history of regular exposure to any form of airborne • Insulation workers asbestos. The presence of calcified pleural plaques on a chest • Asbestos factory workers radiograph indicates exposure to asbestos and helps to distinguish the condition from other causes of pulmonary fibrosis. Once the diagnosis is made, workers should be removed from further exposure. As there may be a synergistic effect between smoking and asbestosis in the development of lung cancer, workers should be encouraged to stop smoking. Extrinsic allergic alveolitis Blue asbestos fibres (left); white asbestos fibres (right) Extrinsic allergic alveolitis is a granulomatous inflammatory reaction caused by an immunological response to certain inhaled organic dusts and some low molecular weight chemicals. Farmer’s lung and bird fancier’s lung remain the most prevalent forms of the disease. 75

ABC of Occupational and Environmental Medicine Acute extrinsic allergic alveolitis usually occurs after Some causes of extrinsic allergic alveolitis exposure to a high concentration of the causative agent. After a sensitising period, which may vary from weeks to years, the Disease Source of antigen Antigen individual develops flu-like symptoms after exposure to the Micropolyspora faeni sensitising antigen. Prolonged illness may be associated with Farmer’s lung Mouldy hay and Thermoactinomyces vulgaris considerable weight loss, but symptoms usually improve within straw Bird serum proteins 48 hours of removal from the causative agent. Bird fancier’s lung Bird excreta Thermoactinomyces sacchari Chronic extrinsic allergic alveolitis is caused either by and bloom Thermophilic chronic exposure to low doses of the causative antigen, or as a actinomycetes consequence of repeated attacks of acute alveolitis over many Bagassosis Mouldy sugar cane years. It results in irreversible pulmonary fibrosis, and the Aspergillus clavatus dominant symptom is exertional dyspnoea. Weight loss may be Ventilation Contaminated Thermophilic considerable but other systemic symptoms are usually absent. pneumonitis air conditioning actinomycetes systems Penicillium casei Diagnosis principally depends on a history of relevant exposure and on identification of a potential sensitising agent Malt worker’s lung Mouldy barley Serum and urine at home or at work. Inspiratory crackles may be heard on proteins examination of the chest, and chest radiography in acute Mushroom Spores released Toluene (TDI) and extrinsic allergic alveolitis may show a ground glass pattern or worker’s lung during spawning diphenylmethane micronodular shadows. In chronic extrinsic allergic alveolitis di-isocyanate (MDI) lung shrinkage in the upper lobes is usually apparent. The Cheese washers’ Mould dust diagnosis is confirmed by detailed pulmonary investigations lung and the demonstration of precipitating antibodies (precipitins) to the causal antigen in the serum. Animal handler’s Dander, dried lung rodent urine Chemical Polyurethane extrinsic allergic foam manufacture alveolitis and spray painting Farmers and pigeon fanciers often deny a relation between causative exposure and symptoms for fear of compromising their livelihood or hobby Further reading Characteristic abnormalities of lung function in extrinsic allergic alveolitis • Meyer JD, Holt DL, Chen Y, Cherry NM, McDonald JC. SWORD • Total lung capacity—reduced • Residual volume—reduced 1999. Surveillance of work-related and occupational respiratory • Vital capacity—reduced disease in the UK. Occ Med 2001;51:204-8. This paper reports on the • Forced expiratory volume in one second (FEV1)—reduced 1999 SWORD results and findings • FEV1/forced vital capacity—normal or increased • Transfer factor for carbon monoxide—reduced* • Mapp CE. Agents, old and new, causing occupational asthma. • Gas transfer coefficient—reduced Occup Environ Med 2001;58:354-9. An up to date review of the *Sensitive indicator of the disease causative agents of occupational asthma, including detailed discussion on isocyanates, latex, flour, enzymes, glutaradehyde, and acrylates. The The picture of victims of the Bhopal disaster is reproduced with paper concludes with an extensive reference list for further reading permission of Rex Features. The table showing the estimated number of cases of work related and occupational respiratory disease is adapted • Kogevinas M, Anto JM, Sunyer J, Tobias A, Kromhard H, Burney P. from Health and Safety Executive Statistics 2000-1 Occupational asthma in Europe and other industrialised areas: a The photograph of a harvester is reproduced with permission from population based study. Lancet 1999;353:1750-4. The results of a Jeremy Walker/Science Photo Library. The photograph of cotton is study of 15 637 young adults in Western European and other with permission from Bill Barksdale/Agstrct/Science Photo Library. industrialised countries. The aim was to verify which occupations carry The photograph of the Bhopal disaster is reproduced with permission a high risk of asthma, and to estimate the proportion of asthma cases in from Rex Features Ltd. the general population attributable to occupational exposures • Health and Safety Executive. Proposals for reducing the incidence of occupational asthma, including an Approved Code of Practice: Control of substances that cause occupational asthma. Sudbury: HSE Books, 2002. This publication details the Health and Safety Executive’s current strategy for reducing the incidence of occupational asthma in the United Kingdom • Baxter PJ, Adams PH, Aw TC, Cockcroft A, Harrington JM. Hunter’s diseases of occupations. London: Edward Arnold, 2000. A multiauthor textbook that contains several chapters on occupational lung disease written by leading experts in the field 76

14 Occupational infections Dipti Patel The pattern of infectious hazards at work changes constantly. The traditional model of infectious disease causation Occupational infections, although not common, can be serious and easy to miss unless there is a high index of suspicion The epidemiological triangle combined with an understanding of infectious disease. Furthermore, infections that are predominantly of historic • An external agent—the organism that produces the infection interest in the developed world continue to pose a considerable • A susceptible host—attributes that influence an individual’s problem in the developing world, and the changing pattern of travel means that those who visit or work overseas remain susceptibility or response to the agent—for example, age, sex, exposed. Drug resistance, the resurgence of certain diseases, lifestyle and the emergence of new or previously unrecognised organisms further complicate matters, as does an increasing • Environmental factors that bring the host and agent together— number of immunocompromised individuals. A detailed occupational history is therefore essential, as this will often factors that affect the agent and opportunity for exposure—for point to the diagnosis of unusual illnesses caused by infectious example, climate, physical surrounding, occupation, crowding hazards. Basic concepts in infectious disease Occupational infections may be work specific or may be common in the general population, but they occur more often • The infectivity of an agent is the proportion of exposed people in those with occupational exposure. Like all occupational diseases, they are mostly preventable. who become infected (attack rate) Healthcare workers are at risk acquiring infections • The pathogenicity is the proportion of people exposed who from human sources such as bloodborne viruses develop clinical disease • The virulence is the proportion of people with clinical disease who become severely ill or die • The infectious dose is the number of organisms that are necessary to produce infection in the host, and this will vary according to the route of transmission and susceptibility of the host Occurrence • An infectious disease is endemic if there is a persistent low to moderate level of occurrence • It is sporadic if the pattern of occurrence is irregular with occasional cases • When the level of disease rises above the expected level for a period of time, it is referred to as an epidemic • An outbreak is two or more cases of illness that are considered to be linked in time and place Reservoir This is any person, animal, arthropod, soil, etc. in which the infectious agent normally resides Mode of transmission This is the mechanism by which an infectious agent is spread from source or reservoir to a susceptible person—that is, direct (touching, biting, eating, droplet spread during sneezing, etc.), indirect (inanimate objects, fomites, vector borne) transmission, or airborne spread (dissemination of microbial aerosol to a suitable port of entry, usually the respiratory tract) Main occupational groups at risk of infection The three main categories of occupational infections are zoonoses, infections from human sources, and infections from environmental sources Zoonotic infections Infections from human sources Infections from environmental sources About 300 000 workers are at risk in the About 2 million people are employed in Examples include legionellosis and tetanus. United Kingdom. Zoonotic infections the health service sector in the United Workers at risk: include anthrax, leptospirosis, Q fever, Kingdom. Infections in this category Lyme disease, orf, and psittacosis. Workers include tuberculosis, erythema infectosum, • Construction workers at risk: scabies, bloodborne viruses, and rubella. • Archaeologists Workers at risk: • Engineering workers • Farmers and other agricultural workers • Military staff • Veterinary surgeons • Healthcare workers • Overseas workers • Poultry workers • Social care workers • Butchers and fishmongers • Sewage workers • Abattoir workers and slaughtermen • Laboratory workers • Forestry workers • Overseas workers • Researchers and laboratory workers—that • Archaeologists (during exhumations) is, animal handlers • Sewage workers • Tanners • Military staff • Overseas workers 77

ABC of Occupational and Environmental Medicine The European Union has introduced the Biological Agents Directive (ongoing with updates since 1993), which is designed to ensure that the risk to workers from biological agents in the workplace is prevented or adequately controlled. In the United Kingdom this directive has been implemented via the Control of Substances Hazardous to Health (COSHH) Regulations 2002 Assessment of health risks of an infectious hazard, and its Hazard classification prevention or control should include: In the United Kingdom biological agents are classified into four hazard groups according to their ability to cause infection • Details of the hazard group the agent belongs to • The diseases it may cause • Group 1—unlikely to cause human disease—for example, • How the agent is transmitted • The likelihood of exposure and consequent disease (including Bacillus subtilis the identification of those who may be particularly susceptible— • Group 2—can cause human disease and may be a hazard to for example, asplenic individuals, those with generalised immune deficiency, pregnant staff), taking into account the employees; it is unlikely to spread to the community, and there is epidemiology of the infection within the workplace usually effective prophylaxis or treatment available—for example, Borrelia burgdorferi • Whether exposure to the hazard can be prevented • Control measures that may be necessary • Group 3—can cause severe human disease and may be a serious • Monitoring procedures • Need for health surveillance, which may include assessment of hazard to employees; it may spread to the community, but there is usually effective prophylaxis or treatment available—for worker’s immunity before and after immunisation example, Bacillus anthracis • Group 4—causes severe human disease and is a serious hazard to employees; it is likely to spread to the community and there is usually no effective prophylaxis or treatment available—for example, Ebola virus When a biological agent does not have an approved classification, the COSHH Regulations 2002 contain guidance on how biological agents should be classified. If in doubt, a higher classification should be assigned Epidemiology SIDAW OPRA Surveillance of Infectious Occupational Physicians As with all occupational ill health statistics, no single source of information provides comprehensive data on occupationally Diseases at Work Reporting Activity acquired infections. In the United Kingdom, the principal data (Reporting by (Reporting by sources, although useful, underestimate the true incidence of occupational infections. consultants in communicable occupational physicians) disease control) Data from UK reporting schemes. The industry with the THOR highest estimated rates of infection per 100 000 workers per year for 1998-2000 was health and social care, followed by SWORD EPIDERM fishing, and agriculture and forestry. Diarrhoeal illnesses Surveillance of Work-related (Reporting by were the most frequently reported conditions and Occupational Respiratory dermatologists) Disease No of cases of infectious Disease disease SIDAW 2000 (estimated) (Reporting by respiratory physicians) Diarrhoeal illness 367 Hepatitis – Legionellosis 4 Voluntary reporting schemes providing data on occupational infections in the United Kingdom Leptospirosis 7 Data from these schemes is integrated into the Health and Occupation Reporting Ornithosis 4 Network (THOR), which is managed on behalf of the Health and Safety Executive. With the exception of SIDAW, reporting is based on a sampling process whereby participating Pulmonary tuberculosis 4 doctors are asked to report incident cases for one month per year. Q fever – Statutory reporting schemes Other (for example, scabies) 175 • Reporting of Injuries Diseases and Dangerous Occurrences Regulations (RIDDOR) 1995. SIDAW total 561 • Social Security (industrial injury) (prescribed disease) Regulations 1985. (See chapter 1) • Public Health (control of diseases) Act 1984. SWORD/OPRA 2000 77 Main information sources for occupational infections in the EPIDERM/OPRA 2000 88 United Kingdom RIDDOR (2000-1 93 provisional) Anthrax (1), chlamydiosis (2), hepatitis (4), legionellosis (14), leptospirosis (12), Lyme disease (3), Q fever (1), tuberculosis (15), others (41) Prescribed diseases (1999-2000) 7 Leptospirosis (1), tuberculosis (4), viral hepatitis (2) Zoonoses Typical painless blister of Orff These are infections that are naturally transmissible from vertebrate animals to man. The World Health Organization estimates that there are over 200 zoonoses worldwide, and around 40 occur in the United Kingdom. 78

Occupational infections Protection of workers exposed to zoonotic infections relies on a number of control measures Control of the disease in the animal reservoir Strict personal hygiene • Stock certification and vaccination (for example, anthrax or • Covering existing wounds with waterproof dressings before work • Prompt cleaning of any cuts or grazes that occur while handling brucellosis) • Quarantine measures (for example, for psittacine birds) animals • Infection free feeds (for example, Salmonella free feed for • Regular and correct hand washing, and avoidance of contact poultry) between unwashed hands and the mouth, eyes, or face • Avoidance of contamination of animal drinking water Personal protective equipment • Test and slaughter policies (for example, for bovine • Waterproof aprons or parturition gowns tuberculosis) • Obstetric gauntlets for lambing or calving • Face protection if there is a risk of splashing from urine or • Good standards of hygiene in stock housing • Regular stock health checks by vets placental fluids • Meat inspection • Plastic or synthetic rubber gloves for oral or rectal examinations • Gloves, overalls, and face protection for slaughtering animals or Safe work practices • Safe handling of animals or animal products (for all zoonotic dressing carcasses infections) • Chainmail gloves for butchers • Safe disposal of carcasses and animal waste (for example, hydatid Other measures disease) • Immunisation of at risk worker (anthrax, Q fever) • Provision of health warning cards (leptospirosis) • Avoidance of equipment likely to cause cuts, abrasions, and grazes NB For protection of laboratory workers advice on control measures has been provided by the Advisory Group on Dangerous Pathogens (Adapted from Health and Safety information sheet “Common zoonoses in agriculture”) Anthrax Patient with cutaneous anthrax Also known as malignant pustule, Woolsorter’s disease, and Ragpicker’s disease, anthrax is a notifiable disease, a prescribed Anthrax has recently received attention because of its disease, and RIDDOR 1995 reportable. It is an acute infection potential for use in bioterrorism. Other potential caused by Bacillus anthracis (a spore forming Gram positive bioterrorism organisms include: bacterium), and the normal animal reservoirs are grazing mammals such as sheep, cattle, and goats. Human anthrax is Organism (disease) Potential source Ability to cause primarily an occupational hazard for workers who process Aerosol or food disease hides, hair, wool, bone, and bone products, but it also occurs in Brucella (Brucellosis) Food, water, or aerosol High vets and agricultural workers who handle infected animals. It is High rare in the United Kingdom (only three cases of anthrax were Clostridium botulinum Aerosol or food supply reported in England and Wales between 1998 and 2001), toxin (Botulism) High occurring in those who work directly or indirectly with infected Aerosol animal products from epizootic areas. Most cases of anthrax Coxiella burnetii High occur in Africa, the Middle East, and the former Soviet Union. (Q fever) Food, water, or aerosol Low Cutaneous anthrax accounts for 95-8% of cases, and occurs Variola virus when the organism enters a cut or an abrasion. After an (Smallpox) incubation period of one to seven days, a small papule develops at this site. Over 24-48 hours, it enlarges, eventually forming a Vibrio cholerae characteristic black ulcer (eschar). If not treated, cutaneous (Cholera) anthrax may progress to bacteraemia, meningitis, and death. Pulmonary and gastrointestinal anthrax occur infrequently, and are the result of inhalation and ingestion of anthrax spores, respectively. In pulmonary anthrax (Woolsorter’s disease) non-specific upper respiratory tract symptoms follow an incubation period of one to six days. Rapid deterioration in respiratory function and death generally follow unless treatment is started promptly. Gastrointestinal anthrax is characterised by severe abdominal pain, watery or bloody diarrhoea, and vomiting. Progression to bacteraemia is usually two to three days. Case fatality in both these forms of anthrax is high. Most naturally occurring strains of anthrax are susceptible to penicillin, although doxycycline and ciprofloxacin have been used recently. Immunisation is also available for at risk workers, and oral antibiotics (ciprofloxacin and doxycycline) have been used as prophylaxis for individuals exposed to anthrax spores. Leptospirosis Leptospirosis is also known as Weil’s disease, canicola fever, haemorrhagic jaundice, mud fever and swineherd disease. It is a notifiable disease, prescribed disease, and RIDDOR 1995 reportable. Leptospirosis is a rare cause of septicaemia caused by pathogenic leptospires belonging to the genus 79

ABC of Occupational and Environmental Medicine Leptospira interrogans (Li). The genus has over 200 serovars; of Farm workers are at increased most importance in humans are Li hardjo (cattle associated risk of catching animal borne leptospirosis), Li icterohaemorrhagiae (Weil’s disease), and diseases Li canicola. The principal animal reservoirs are cattle, rats, and dogs, respectively. Transmissible spongiform encephalopathies (TSEs) Human TSEs The distribution of human disease depends on the local • Creutzfeldt-Jakob disease (CJD) prevalence of animal infection and local environmental • Variant CJD (vCJD) conditions. At risk occupational groups include agricultural • Gerstmann Sträussler Scheinker syndrome workers, farmers, vets, miners, abattoir workers, and sewer and • Kuru canal workers. In 2001 there were 25 notified cases of • Fatal familial insomnia leptospirosis in England and Wales (predominantly caused by Animal TSEs Li hardjo). • Scrapie (sheep and goats) • Bovine spongiform encephalopathy (BSE) (cattle) Leptospirosis is usually acquired by direct contact with • Transmissible mink encephalopathy (farmed mink) infected animals or their urine, contaminated soil, food, or water • Chronic wasting disease (deer) (a hazard for those indulging in watersports). The incubation • Feline spongiform encephalopathy (domestic cats and captive period is usually five to 14 days, and symptoms, which are not serotype specific, typically consist of fever, flu-like symptoms, exotic felines) headache, myalgia, photophobia, and conjunctival injection. In severe cases (often associated with Li icterohaemorrhagiae) • Spongiform encephalopathy (captive exotic ungulates) haemorrhage into skin and mucous membranes, vomiting, jaundice, and hepatorenal failure may occur. A number of measures have been taken to minimise disease transmission among animals and humans, and although there is Mild infection is often self limiting, but penicillin, no clear evidence of occupational risk, advice on safe working erythromycin, and doxycycline are all effective treatments. For practices has been provided by the Advisory Committee on more severe disease, intensive and specialised therapy is Dangerous Pathogens. Those potentially at risk include workers necessary. in abattoirs, slaughterhouses and rendering plants; farmers; neurosurgeons; pathologists; and mortuary technicians Immunisation of animals is possible for certain serovars, and in some countries (Japan, Italy, Spain) immunisation of at risk workers against certain serovars is available. In the United Kingdom, workers who may be exposed to leptospires usually carry an alert card provided by their employer to warn their doctors should they develop such symptoms. Transmissible spongiform encephalopathies (TSEs) Prion disease These are a group of progressive and fatal neurological disorders occurring in humans and certain animal species. TSEs are thought to be caused by infectious proteins (prions) that are unusually resistant to conventional chemical and physical decontamination. They do not seem to be highly infectious and, with the exception of scrapie, do not seem to spread through casual contact. Bovine spongiform encephalopathy (BSE) was first recognised in British cattle in 1986. Its origin is still uncertain, but it probably originated in the early 1970s, developing into an epidemic because of changing practices in rendering cattle offal to produce animal protein in the form of meat and bonemeal, which was included in compound cattle feed. This resulted in the recycling and wide distribution of BSE. In 1996, a previously unrecognised form of Creutzfeldt-Jakob disease (CJD) occurring in younger patients (range 14-53 years, mean 28 years), with a different symptom profile and different postmortem changes in the brain tissue, was identified in the United Kingdom. The Government’s Spongiform Encephalopathy Advisory Committee concluded that the most likely explanation for the emergence of this variant CJD (vCJD) was that it had been transmitted to humans through exposure to BSE as a result of consumption of contaminated bovine food products. A major concern now is the risk of transmission in a healthcare setting. Although there have been no reported cases of nosocomial transmission of vCJD, an expert group has been established by the UK government to advise on prevention and management of possible exposures. 80

Occupational infections The incubation period of vCJD is unknown, but is likely to Although it is likely that most of the UK be several years. The infectious dose is also unknown, and is population has been exposed to BSE, the true likely to be dependent on the route of exposure. However, by number of individuals who have been February 2002, a total of 114 individuals throughout the United infected is not known Kingdom (106 dead and 8 alive) were considered to have had definite or probable vCJD. There is currently no evidence to Reasons that vCJD might be spread from person to person link any cases of vCJD with surgical procedures or with in healthcare settings transmission by blood, but the possibility cannot be ruled out. • Classical CJD has been transmitted from person to person by It is already current practice to dispose of instruments used a range of medical procedures including surgery, grafts or on anyone showing symptoms of vCJD. A problem, however, transplants, and treatment with pituitary extracts, and about 1% occurs in those who have presymptomatic disease; precautions to of classical CJD cases in the past are considered to have been avoid this theoretical risk of transmission are therefore essential. iatrogenic Any assessment of risk of transmission from instruments must consider a wide range of scenarios, and precautionary measures • Abnormal prion protein has been shown in the lymphoreticular should be taken against risks that might occur, even if the level of risk is not known. The key message in reducing any risk of vCJD tissue (tonsils, spleen, and lymph nodes) of patients with transmission is the rigorous implementation of washing, established vCJD decontamination, and general hygiene procedures. • Abnormal prion protein has been shown in the appendix of In January 2001, a recommendation that single use instruments were used for tonsillectomy and adenoidectomy a patient who subsequently developed vCJD surgery was made. This recommendation was withdrawn in December 2001 because adverse incidents (mainly • Although, to date, the transmissible agent has not been shown in haemorrhage, but also one death) were reported after the introduction of single use instruments. It was felt that on blood, it is possible that abnormal prion protein, at balance, the single use instruments represented an actual risk concentrations not detectable with current techniques, may be to patients, whereas the concerns regarding vCJD transmission associated with circulating B lymphocytes and with other cells of were only theoretical. Further information is available at the immune and circulatory systems http://www.open.gov.uk/doh/coinh.htm. • Abnormal prion protein has been shown to be highly tenacious Infections from human sources and may not be inactivated by conventional sterilisation and These infections are of most relevance to healthcare workers. decontamination procedures They are important because healthcare workers are at high risk of acquiring infections occupationally and they are also a potential source of infection to their patients, particularly those who are immunologically impaired. Bloodborne viruses Exposure prone procedures are invasive procedures where Occupational exposure to blood or body fluids poses a small there is risk that injury to the worker may result in the exposure risk of transmission of bloodborne pathogens. Those of a patient’s open tissues to the blood of the worker. These presenting the greatest crossinfection hazard are HIV, and incude procedures where a healthcare worker’s gloved hand hepatitis B and hepatitis C viruses. Although healthcare staff may be in contact with sharp instruments or tissues inside a are at greatest risk, other occupational groups (for example, patient’s open body cavity, wound, or confined anatomical space police officers) may also be exposed. where the hands may not be completely visible at all times The risk of infection depends on the type and severity of the exposure, the infectivity of the source patient, the immune status of the exposed healthcare worker, and the availability of treatment after exposure. Prevention entails minimising exposure to blood or body fluids, and consists of strict infection control, adherence to universal precautions, immunisation against hepatitis B, and prompt management of any occupational exposure. Healthcare workers infected with bloodborne viruses can potentially transmit infection to their patients, and although the risk is small, guidelines exist in many countries to reduce this risk further. In the United Kingdom, all healthcare workers who perform exposure prone procedures are required to provide evidence that they are immune to hepatitis B as a result of immunisation, or that they are not HBe antigen (HBeAg) positive. Because of transmissions of HBV associated with codon 28 precore mutations, those who are HB surface antigen positive, but HBeAg negative, must now be tested for hepatitis B virus DNA; they may perform exposure prone work provided that their HB viral load is below 103 genome equivalents per millilitre, and this is subject to annual testing. 81

ABC of Occupational and Environmental Medicine Risk of transmission of bloodborne viruses Low risk body fluids (unless visibly bloodstained) High risk body fluids • Urine • Faeces • Cerebrospinal fluid • Vomit • Peritoneal, pleural, pericardial fluid • Synovial fluid Significant exposures • Amniotic fluid • Breast milk • Percutaneous injury • Vaginal secretions • Exposure of broken skin • Semen • Exposure of mucous membrane • Saliva associated with dentistry • All visibly blood stained fluid Hepatitis C virus: 1.8% • Unfixed organs or tissues Hepatitis B virus: 37-66% from HBeAg positive source; 23-37% from HBsAg positive source Estimated risk of seroconversion after percutaneous exposure Effective immunisation is available for hepatitis B virus and 80-90% HIV: 0.32% (based on data of 6202 healthcare workers). Risk of of individuals mount an adequate response mucous membrane exposure is 0.09%, and there have been no transmissions associated with exposure of intact skin. In the United Hepatitis C virus Kingdom there have to date (March 2002) been five definite No effective PEP exists. Recommendations for post-exposure occupationally acquired transmissions of HIV. Worldwide by 1999, management are therefore intended to achieve early identification 102 definite and 217 possible cases of occupationally acquired HIV of infection, with appropriate specialist referral. Although had been reported consistent data are lacking, one uncontrolled trial has shown a substantially better response rate of early treatment using The risk of percutaneous exposure is increased if the injury is interferon compared with treatment of patients with chronic deep, the device is visibly blood stained, the injury is from a needle disease placed in artery or vein, or the source patient has terminal HIV infection Post-exposure prophylaxis (PEP) HIV Most countries now recommend a four week course of zidovudine with lamivudine, and many recommend the addition of a protease inhibitor. The choice of drugs, doses, route of administration, and the length of PEP are somewhat empirical. However, because most studies indicate a time limited response to PEP, the need for timely and early therapy is vital. In the United Kingdom, HIV PEP generally consists of zidovudine and lamivudine (Combivir) with nelfinavir, indinavir, or soft gel saquinavir (March 2002) Hepatitis B virus Hepatitis B virus immunoglobulin (HBIG) is available for passive protection and is normally used in combination with hepatitis B vaccine to confer passive-active immunity to susceptible individuals after exposure. The post-exposure efficacy of combination HBIG and hepatitis B vaccine has not been evaluated in the occupational setting, but increased efficacy (85-95%) has been observed perinatally. Although HBIG may not completely inhibit virus multiplication, it may prevent severe illness and the development of a chronic carrier state Individuals who, as a result of testing, are found to be Recent UK guidance for hepatitis C hepatitis C RNA positive should not perform exposure prone procedures. However, hepatitis C infected workers who have • Healthcare workers who carry out exposure prone procedures been successfully treated with antiviral therapy and remain hepatitis C virus RNA negative six months after finishing and already know themselves to be infected with hepatitis C treatment should be able to resume exposure prone should be tested for hepatitis C virus RNA (if not already done) procedures or start professional training for a career that relies on the performance of exposure prone procedures. • All healthcare professionals intending to undertake professional HIV testing is not compulsory for healthcare workers in the training for a career that relies on the performance of United Kingdom and many other countries. In the exposure prone procedures should be tested for hepatitis C United Kingdom, professional regulatory bodies state that infection workers who may have been exposed to HIV have an ethical responsibility to be tested. If found to be HIV infected, • Those who perform exposure prone procedures and believe that exposure prone work is prohibited. The UK Department of Health is currently reviewing their policy. they may have been exposed to hepatitis C should seek and follow confidential and professional advice on whether they should be tested for hepatitis C Tuberculosis Tuberculosis is a notifiable disease, a prescribed disease, and RIDDOR 1995 reportable. Mycobacterium tuberculosis continues to be the leading cause of adult death from any single infectious agent worldwide. 82

Occupational infections Bloodborne viruses and risk to patients Hepatitis B virus HIV • A number of look-back studies involving surgical staff from 1975 • In the United Kingdom, the Expert Advisory Group on AIDS to 1990 have identified transmission risks of 0.9-20% (EAGA) provides guidance on look-back procedures for HIV. As • The most recent look-back exercise for hepatitis B virus in the UK studies of over 30 000 patients after look-back exercises have shown no evidence of transmission of HIV to patients, it is likely United Kingdom was in 2001. About 350 patients were contacted that look-back procedures for HIV in the United Kingdom will in Fife, when infection in two patients was traced back to one stop healthcare worker • Two incidents of transmission from a healthcare worker to a • A surgeon infected with hepatitis B (Dr Gaud) who lied about patient have been reported: a Florida dentist who infected six his infectivity was convicted and jailed for the common law patients, and a French orthopaedic surgeon who infected one charge of “public nuisance” after knowingly operating on patient patients and putting them at risk of infection • Dr Patrick Ngosa, an HIV positive obstetrician, was removed from Hepatitis C virus the UK General Medical Council’s Register in 1997 when it was • In the United Kingdom there have been five patient notification discovered that he had refused to have an HIV test and continued to perform exposure prone procedures after learning that a exercises after investigations of hospital acquired hepatitis C former sexual partner was HIV positive. A total of 1750 women on infection. Since 1994 there have been 15 documented whom he had operated were sent letters informing them that transmissions of hepatitis C virus to patients from infected there was a possibility that they had been exposed to HIV healthcare workers during exposure prone procedures The emergence of multidrug resistant tuberculosis (MDRTB), Multidrug resistant tuberculosis (MDRTB) with its high case fatality, its prolonged sputum positivity (and consequently, high transmission risk), and its complex MDRTB is tuberculosis resistant to at least isoniazid and rifampicin treatment has re-emphasised the importance of tuberculosis control. Effective control of MDRTB requires a multidisciplinary approach involving the hospital infection control team, microbiologist, Tuberculosis remains a hazard in the healthcare setting, tuberculosis physician, consultant in communicable disease and incidence in healthcare workers parallels (but is higher control, engineers, and occupational health than) that in the community; a study in the mid-1990s found about a twofold increased risk of tuberculosis among healthcare • Visitors to patients with known or suspected MDRTB should be workers in England and Wales. Healthcare workers should therefore be protected against infection, and measures should kept to a minimum be taken to detect tuberculosis in new or existing staff in order to protect their patients and colleagues. Protection begins at • The number of healthcare workers exposed to MDRTB patients pre-employment, and continues with strict infection control measures for nursing infected patients. should be kept as low as possible In the United Kingdom, protection of healthcare workers • All who enter the rooms of MDRTB patients should wear suitable should follow the guidelines produced by the Joint Tuberculosis Committee of the British Thoracic Society. particulate masks that filter down to particles of 1 micron in diameter Adults with non-pulmonary tuberculosis can usually be nursed on general wards, but those with pulmonary • Staff should wear masks during aerosol generating procedures, tuberculosis should initially be admitted to a single room vented to the open air until their sputum status is known. such as sputum induction, bronchoscopy, and pentamidine Those with smear positive sputum should be managed as therapy. These procedures should only be performed in suitably infectious. In the case of known or suspected MDRTB, ventilated facilities particular care must be taken, and patients should be admitted to a negative pressure single isolation room until MDRTB is • Individuals who have not been checked for immunity to excluded or until sputum smears have been negative on three consecutive occasions over 14 days. tuberculosis, or those with a negative skin test who have not received BCG vaccination should avoid contact with MDRTB Outbreaks of MDRTB in the United States and Europe have patients, as should those who are immunocompromised emphasised the importance of control. These outbreaks have occurred predominantly in institutional settings (prisons, The decision to discontinue strict isolation and infection control residential homes, and hospitals) and have mainly been in procedures should only be made after discussion between the HIV infected patients. Contributory factors in these outbreaks clinician with responsibility for the patient, the hospital infection included lapses in respiratory isolation, inadequate ventilation control team, occupational health, and a consultant in in isolation rooms, and “immunocompromised convergence” communicable diseases (the assembling of immunocompromised HIV infected patients in institutions). 83

ABC of Occupational and Environmental Medicine Pre-employment questionnaire Suspicious No Yes symptoms Medical assessment chest radiograph No Yes Normal No Working with Yes patients or clinical specimens Prior No BCG scar or document Heaf test Yes Yes No Grade 0,1 Further history No Suspicious Yes symptoms Chest radiograph and medical assessment Yes No Normal Chest No Give Inform Chest clinic action BCG and advise clinic Protection of healthcare workers with tuberculosis When a patient or member of staff is found to have Complications of varicella zoster virus tuberculosis, infection control and occupational health staff have to assess the need for contact tracing. In the United Kingdom, • Severe disease due to fulminating varicella pneumonia is more likely most staff are not considered to be at special risk and should be reassured and advised to report any suspicious symptoms. Those in adults, especially pregnant women, and smokers who are immunocompromised, have undertaken mouth to mouth resuscitation, prolonged high dependency care, or • Pregnant women are at greatest risk late in second or early third repeated chest physiotherapy without appropriate protection should be regarded as close contacts and followed up according trimester to national guidelines. Similar precautions should be taken if the index case is highly infectious. • In the immunocompromised and neonates, disseminated or Chickenpox haemorrhagic varicella is more likely Chickenpox is a systemic viral infection resulting from primary infection with varicella zoster virus. It is highly infectious and • The risk to fetus and neonate from maternal infection relates to transmitted directly by personal contact or droplet spread, and indirectly through fomites. Shingles (herpes zoster) is a gestation at time of infection reactivation of dormant virus in the posterior root ganglion – First 20 weeks—congenital varicella syndrome (limb hypoplasia, and can be a source of infection generally by contact with the skin lesions, but occasionally by the respiratory route in microcephaly, hydrocephalus, cataracts, growth retardation, and immunocompromised individuals. skin scarring) – Second and third trimester—herpes zoster in otherwise healthy infant Primary infection in adults can be severe, resulting in – A week before to a week after delivery—severe and even fatal disease in a higher frequency of complications such as pneumonia, the neonate (particularly premature babies) encephalitis, and hepatitis, but its main importance is the risk to non-immune pregnant women and the immunosuppressed. • Human varicella zoster immunoglobulin (VZIG) is available and can Although the prevalence of seropositivity for varicella zoster be given for post-exposure prophylaxis in individuals who fulfill the virus in healthcare workers in temperate climates is high following conditions: (90-98%), nosocomial exposure to the virus is a major – a clinical condition that increases risk of varicella infection occupational health problem requiring non-immune healthcare – no antibodies to varicella zoster virus workers to be excluded from patient contact from day 8 to 21 – substantial exposure to chickenpox or herpes zoster after a substantial exposure. A live attenuated vaccine is now available in many parts of the world. • A substantial exposure to varicella zoster virus depends on: – the type of infection in the index case—for example, the risk of acquiring infection from an immunocompetent individual with non-exposed shingles is remote – the timing of the exposure in relation to onset of rash in the index case—the critical time for chickenpox or disseminated zoster is 48 hours before the onset of rash until crusting of lesions for varicella zoster virus, and day of onset of rash until crusting in localised zoster – closeness and duration of contact—contact in same room Ͼ15 minutes, or face to face contact • The recommendation that VZIG is used for exposed non-immune pregnant women during the first 20 weeks of pregnancy is based on biological plausibility. No evidence exists showing that the risk of congenital varicella syndrome is reduced • VZIG is not recommended for healthy healthcare workers, but in the United States, varicella vaccine is recommended for use in susceptible individuals after exposure; data from hospital and community settings suggest that it is effective in preventing illness or modifying severity if used within three days of exposure 84

Occupational infections Other infections Legionnaire’s disease • Travel abroad is a major risk factor for Legionnaire’s disease in Other infections worth mentioning include skin infection in engineers associated with the re-use of cutting oils (which can the United Kingdom, with nearly 50% of cases being contracted lead to oil mists being contaminated with bacteria and fungi), abroad pseudomonal otitis externa in deep sea divers who use saturation techniques, and legionellosis (which can occasionally • About 15% of UK cases are linked to local outbreaks (caused by be occupationally acquired). Finally, travel associated infections are becoming an important cause of occupationally acquired wet cooling systems or hot water systems), and roughly 2% are disease with the increase in international business travel and hospital acquired. Many cases are sporadic, or from an overseas workers (see ABC of Healthy Travel). unidentified source Legionellosis (Legionnaire’s disease, Pontiac fever) • Hospital outbreaks in particular have high case fatalities This infection is RIDDOR 1995 reportable. It is an acute • The highest risk of infection occurs with water systems leading to bacterial infection caused by a Gram negative bacillus belonging to the genus Legionella. Two clinical presentations the aerosolisation of water that is stored at temperatures of are recognised: Legionnaire’s disease and Pontiac fever, and 25-45ЊC. This includes: the majority of infections are due to L. pneumophila. The – wet cooling systems (for example, cooling towers and bacillus is an ubiquitous aquatic organism that thrives in warm environments (25-45ЊC, but preferably at 30-40ЊC), and is often evaporative condensers) isolated from natural habitats (rivers, creeks, hot springs) and – hot water systems (especially showers) from artificial equipment where the temperature is maintained – whirlpool spas at levels favouring bacterial proliferation. – indoor and outdoor fountain and sprinkler systems – humidifiers Transmission of infection is from inhalation of – respiratory therapy systems contaminated aerosols, and both Legionnaire’s disease and – industrial grinders Pontiac fever present initially with non-specific flu-like symptoms. Pontiac fever occurs after an incubation period of • Prevention of infection relies on ensuring that equipment and 4 to 66 hours, and is a self limiting non-pneumonic form of the infection. By contrast, the incubation period for Legionnaire’s systems are kept as clean as possible, and disinfected regularly. disease is two to ten days. Initial symptoms of fever, malaise, Where possible, water temperatures should be kept above 50 ЊC anorexia, and myalgia are followed by progression to or below 20ЊC. Use of biocides may also need to be considered. pneumonia and associated multisystem involvement, with In the United Kingdom, the Health and Safety Executive diarrhoea, vomiting, confusion, and renal failure. Case fatality provides guidance on the prevention and control of legionellosis can range from 5% to 15%, but may be higher in outbreaks. Legionella bacteria Treatment generally consists of erythromycin (although rifampicin may be used as an adjunct). If infection is confirmed, local public health authorities need to be notified as contacts may need to be identified, and the source of infection needs to be established and appropriately controlled. Conclusion The extent of occupationally acquired infections is unknown, Further reading but it is likely that they are extremely common, particularly mild infections in agricultural and healthcare workers. • Heponstall J, Cockcroft A, Smith R. Occupation and infectious Preventing infection is an important aspect of occupational health practice as it will impact favourably on communicable diseases. In: Baxter P, Adams PH, Cockroft A, Harrington JM, disease in the general population. Similarly, the control of eds. Hunter’s diseases of occupations. London: Edward Arnold, communicable disease in both the general (and animal) 2000:489-517. This chapter provides comprehensive information on population will decrease the risk to certain occupational groups. occupational infections The table showing Data from UK reporting schemes depicting the • Hawker J, Begg N, Blair I, Reintjes R, Weinberg J. Communicable industries with the highest estimated rates of infection is adapted from Health and Safety Executive Statistics 2000-1. The figures showing the disease control handbook, 1st ed. Oxford: Blackwell Science Ltd, protection of workers with tuberculosis are adapted from the guidelines 2001 of the Joint Tuberculosis Committee of the British Thoracic Society. Control and prevention of tuberculosis in the United Kingdom: code of • Chin J. Control of communicable diseases manual, 17th ed. practice 2000. Http://www.brit-thoracic.org.uk Washington: American Public Health Association, 2000. Both these references, although aimed at public health practitioners, provide extensive detail on communicable diseases, their epidemiology, clinical features, prevention, and control • http://www.who.int • http://www.cdc.gov • http://www.phls.co.uk These websites are excellent resources for information on infectious diseases (both occupational and non-occupational) • http://www.open.gov.uk/doh/dhhome.htm The UK department of health website is particularly useful for information on bloodborne viruses and BSE • http://www.hse.gov.uk This site provides practical and clear information on prevention and control of a variety of infectious hazards in the workplace, and is also a source of occupational ill-health statistics 85

15 Occupational cancers John Hobson The first report of cancer caused by occupational exposure was Foundry workers may be exposed to a complex mixture of carcinogenic in 1775 by Percival Pott, a British surgeon who described scrotal agents in fumes cancer in boy chimney sweeps. A century later, in 1895, Rehn, a German surgeon working in Frankfurt, treated a cluster of Of all the occupationally related diseases, cancer evokes three cases of bladder cancer in workers at a local factory particular concern and strong emotions, because of the producing aniline dyestuffs from coal tar. opportunity afforded for attribution, blame, and compensation. However, occupational cancers also have unique potential for Occupational cancer is any malignancy wholly or partly prevention caused by exposures at the workplace or in occupation. Such exposure may be because of a particular chemical (such as International Agency for Research on Cancer (IARC) ␤-naphthylamine), a physical agent (such as ionising radiation), classifications to date a fibre like asbestos, a biological agent (such as hepatitis B virus), or an industrial process in which the specific carcinogen Group Carcinogenic Number may elude precise definition (such as coke production). 1 Probably carcinogenic 87 2A Possibly carcinogenic 63 Overall it is estimated that 4% of all cancers are caused by 2B Unclassifiable as to carcinogenicity in 233 occupation (range 2-8%), but for bladder cancer this may be as 3 humans 490 high as 20%. In the working population as many as one in five Probably not carcinogenic to humans cancers may be attributable to exposure in the workplace. In 4 1 (caprolactam) England and Wales at least 3000 men die each year from potentially preventable malignancies. The International Agency for Research on Cancer (IARC) was set up to identify carcinogenic hazards to humans. To date, 874 chemicals, groups of chemicals, complex mixtures, occupational exposures, cultural habits, and biological and physical agents have been evaluated. The findings have been published in 79 monographs and eight supplements. Mechanisms of cancer Cancer is a genetic disorder of somatic cells and can be triggered by the genotoxic action of carcinogens. There are five or six independent stages of carcinogenesis, each of which is rate limiting. The best available model is colorectal cancer, which requires seven independent genetic events. The three key stages are initiation (by a mutagen), promotion (where development of tumours is enhanced by other stimuli to cell proliferation such as lung fibrosis), and progression (development of malignant tumours from benign neoplasms). Mutations in tumour suppressor genes (for example, p53) are particularly important, and half of all cancers contain p53 mutations, of which there are 6000 possible point mutations. Several environmental and occupational carcinogens are linked to p53 mutations—for example, ultraviolet light and skin cancer, and tobacco and oral cancer. Other factors linked with p53 include alcohol, vinyl chloride, and asbestos. Most carcinogens are genotoxic (DNA reactive) and cause mutation. There is no threshold below which they are not carcinogenic and therefore exposure levels are set at acceptable levels. Tests for genotoxicity such as Ames and fluorescent in situ hybridization (FISH) are now well established. The Ames test is the most widely used procedure for assessing the mutagenicity of chemicals. The relative mutagenic potency of an agent is indicated by the number of bacterial colonies growing on a plate containing the toxic agent relative to those growing on a plate containing normal medium. FISH is used to assess chromosomal abnormalities. Epigenetic carcinogens (also known as non-genotoxic or cocarcinogens) act more directly on the cell itself, through 86

Occupational cancers hormonal imbalances, immunological effects, or promoter Thick walled mesothelioma of activity, to cause abnormal cell proliferation and chromosomal pleura with haemorrhagic aberrations that affect gene expression. These carcinogens have cavitation in a former a threshold dose for carcinogenicity and it is possible to set insulation worker exposure levels. There is probably a minimal threshold dose as well as a clear dose-response relation influencing the occurrence of cancers. For example, all workers involved in distilling ␤-naphthylamine eventually developed tumours of the urothelial tract, whereas only 4% of rubber mill workers who were exposed to ␤-naphthylamine (a contaminating antioxidant (at 0.25%) used in making tyres and inner tubes) developed bladder cancer over a 30 year follow up. Polymorphisms are different responses to the same factor such as a drug. Slow acetylators who are heavy smokers are 1.5 times more likely to get bladder cancer if exposed to carcinogens. Certain polymorphisms increase the risk of mesothelioma 7.8 times. It will be possible in the future to rapidly and cheaply test individuals for polymorphisms and genotypes. Sites of cancers Carcinogens are organotropic. In the United Kingdom the most commonly affected sites are the lung (mesothelium) (75%), bladder (10%), and skin (1%). Other sites affected are the haemopoietic system, nasal cavities, larynx, and liver. Natural course of cancers Diagnosis of work related cancer Occupationally related cancers are characterised by a long • Detailed lifelong occupational history latent period (that is, the time between first exposure to the • Comparison with a checklist of recognised causal associations causative agent and presentation of the tumour). This latency is • Confirmation of requisite exposure not usually less than 10 to 15 years and can be much longer • Search for additional clues: shift to a younger age, presence of (40-50 years in the case of some asbestos related mesotheliomas): presentation can therefore be in retirement signal tumours, other cases and “clusters,” long latency, absence rather than while still at work. However, susceptibility to of anticipated aetiologies, unusual histology or site occupational carcinogens is greater when the exposure occurs at younger ages. An occupationally related tumour does not differ substantially, either pathologically or clinically, from its “naturally occurring” counterpart. Recognition and diagnosis For a group of workers, occupational cancer is evidenced by a clear excess of cancers over what would normally be expected. Some common malignancies that can be work related also have a well recognised and predominant aetiology related to other agents, diet, or lifestyle (for example, lung cancer from smoking). There are, however, some features that may help to distinguish occupational cancers from those not related to work. History taking Taking a patient’s occupational history is paramount. It should be defined in detail and sequentially. For example, a holiday job in a factory that lasted only a few months could easily be overlooked, but it may have included delagging a boiler or handling sacks of asbestos waste. Signal tumours Rubber workers in mill room Several uncommon cancers are associated with particular occupations. Thus, an angiosarcoma of the liver may indicate past exposure to vinyl chloride monomer in the production of polyvinyl chloride, although there have been no cases in workers exposed since 1969. A worldwide registry of all exposed workers exists. 87

ABC of Occupational and Environmental Medicine Age A younger age at presentation with cancer may suggest an occupational influence. For example, a tumour of the urothelial tract presenting in anyone under the age of 50 years should always arouse suspicion. Patients’ information Patients may speak of a “cluster” of cancer cases at work, or they may have worked in an industry or job for which a warning leaflet has been issued. Prevention Cystoscopic view of papillary carcinoma of the bladder in a 47 year old rubber worker Primary prevention seeks to prevent the onset of a disease. Secondary prevention aims to halt the progression of a disease once it is established. Tertiary prevention is concerned with the rehabilitation of people with an established disease to minimise residual disabilities and complications or improve the quality of life if the disease itself cannot be cured. Levels of prevention Stages Outcomes Health Asymptomatic Symptomatic Disability Recovery Death Intervention Health Presymptomatic Early Rehabilitation strategies education, screening diagnosis and immunisation, Secondary prompt Level of environmental effective prevention measures and treatment social policy Tertiary Primary Adapted from Donaldson and Donaldson, 1999. Primary prevention of occupationally related cancers Action for primary prevention of occupational cancers depends essentially on educating employers and employees; • Recognition of presence of hazards and risks firstly about recognising that there is a risk, and then about the • Education of management and workforce practical steps that can be taken to eliminate or reduce • Elimination of exposure by substitution and automation exposure and to protect workers. Modern risk based legislation • Reduction of exposure by engineering controls (such as local now directs these educational and practical measures. exhaust ventilation and enclosure, changes in handling, and Secondary prevention altering physical form in processing) Screening procedures may enable earlier diagnosis, but there is little evidence to suggest that most screening makes a • Monitoring of exposure and maintaining plant difference to outcome. Screening is of proven benefit in • Protection of workers with personal protective equipment cutaneous cancers of occupational origin, mainly because of • Limiting access the excellent prognosis afforded by treatment. Routine skin • Provision of adequate facilities for showering, washing, and inspections should be initiated where there is exposure to known skin carcinogens. Routine urine cytology has been changing carried out in many industries where there has been previous exposure to known carcinogens. It is possibly of benefit but this • Legislative provisions has not been proven. ␤-Naphthylamine was withdrawn from use by 1950, but many former workers continue to participate in Criteria for screening urine cytology screening programmes. Once commenced, • Is the condition an important health problem? surveillance should be lifelong. In the United Kingdom it is • Is there a recognisable early stage? recommended workers exposed to 4,4-methylene-bis-(2- • Is treatment more beneficial at an early stage than at a later chloroaniline) (MbOCA) should have their urinary levels of MbOCA and its N-acetyl metabolites checked, but periodic stage? urine cytology for those exposed remains controversial. Screening for lung and liver cancer is not of benefit. • Is there a suitable test? • Is the test acceptable to the population? • Are there adequate facilities for diagnosis and treatment? • What are the costs and benefits? • Which subgroups should be screened? • How often should screening take place? 88

Occupational cancers Legislation and statutory compensation Essential legislative provisions in the United Kingdom and the Benefits and disadvantages of screening European Union are comprehensive. Ten types of cancer are prescribed diseases and are eligible for industrial injuries Benefits benefit. Some cancers are reportable under the Reporting of Injuries, Diseases, and Dangerous Occurrence Regulations 1995 • Improved prognosis for some cases detected by screening (RIDDOR), although many occur in those who have retired. • Less radical treatment for some early cases Most occupational cancers recorded or eligible for benefit • Reassurance for those with negative test results are mesotheliomas. In 2000, 652 people received benefits in the United Kingdom for mesothelioma, which is less than Disadvantages half the number of deaths recorded as caused by this disease (1595 deaths in 1999). About 80 people with other • Longer morbidity for cases whose prognosis is unaltered occupational cancers receive benefits each year, these being • Over treatment of questionable abnormalities split between bladder cancer and asbestos related lung cancer. • False reassurance for those with false negative results Bladder cancers have slowly increased over the past decade, • Anxiety and sometimes morbidity for those with false positive whereas lung cancers have decreased. The figure for asbestos related lung cancers substantially under-represents the true results number. • Unnecessary medical intervention for those with false positive results • Hazard of screening test • Resource costs: diversion of scarce resources to screening programme Specific carcinogens Metals and metalliferous compounds Main legislative provisions in the United Kingdom Arsenic, beryllium, cadmium, chromium(VI), nickel, and iron are considered to be proven human carcinogens, either as the • Control of Substances Hazardous to Health (COSHH) metal itself or as a derivative. The risk from iron is related only to mining the base ore and is caused by coincidental exposure Regulations 2002 and associated approved code of practice on to radon gas. In foundries, where there is concomitant the Control of Carcinogens exposure to several agents in a complex mix of emanating fume, the responsible agents are not clearly defined. • European Commission Carcinogens Directive (90/934/EEC) • Chemical Agents Directive (98/24/EC) With all the metallic carcinogens, the lung is the main • Chemicals (Hazard Information and Packaging) Regulations target organ, but other potential sites are shown in the table. The main occupational exposures occur in the mining, 1999 (CHIP) smelting, founding, and refining of these metals, and less commonly in secondary industrial use. • Ionising Radiations Regulations (1999) • Control of Asbestos at Work Regulations (1998) • Reporting of Injuries, Diseases, and Dangerous Occurrences Regulations (RIDDOR) 1995 Aromatic amines Metalliferous carcinogens Target organ Aromatic amines are among the best known and most studied Lung and skin of chemical carcinogens. The bladder is the main target organ, Agent Lung but any site on the urothelial tract composed of transitional cell Lung, prostate gland epithelium can be affected—that is, from the renal pelvis to the Arsenic Lung prostatic urethra. Tumours of the upper urothelial tract (renal Beryllium Lung, nasal sinuses pelvis or ureter) are very rare, and a cluster of these signal Cadmium tumours usually heralds an underlying risk of occupational Chromium (hexavalent) Lung cancer. The carcinogenic potential of aromatic amines lies not Nickel Lung, digestive tract in the parent compound but in a metabolite formed in the liver Iron in: and excreted through the urinary system. Haematite mining (radon) The occupations classically associated with risk from these Iron and steel founding chemicals were in the industries’ manufacturing chemicals and dyestuffs. In the early 1950s an investigation of bladder cancers Aromatic amine carcinogens in workers in British chemical industries showed that individuals exposed to benzidine and 2-napthylamine had Proved a 30 times greater risk of developing bladder cancer than the general population. Occupational bladder cancer became a • 4-Aminobiphenyl (xenylamine) and its nitro derivatives prescribed disease in 1953. • ␤-Naphthylamine • Benzidine Antioxidants contaminated with ␤-Naphthylamine were • Auramine and magenta used in the rubber and cable making industries until the end of 1949 (when they were universally withdrawn), and they caused Probable an excess of bladder cancer. The level of contamination was only about 0.25%, yet it almost doubled the risk for the • Polycyclic aromatic hydrocarbons workforce so exposed. People who started work in the rubber industry after 1951 seem to have no excess risk. Possible There is now increasing evidence that some polycyclic • The hardener MbOCA (4,4-methylene-bis-(2-chloroaniline)) aromatic hydrocarbons can act as urinary tract carcinogens. 89

ABC of Occupational and Environmental Medicine This is reflected in excesses seen in aluminium refiners and in Occupations causally associated with urothelial tract cancers painters exposed to solvents. • Dyestuffs and pigment manufacture Asbestos • Rubber workers (in tyre, tube, and cable making before 1950) Few natural materials used in industry have been the subject of • Textile dyeing and printing more epidemiological and pathological research than the • Manufacture of some chemicals (such as 4,4-methylene-bis- fibrous mineral, asbestos. Lung cancer because of asbestos was first reported in the 1930s and its association was confirmed in (2-chloroaniline) (MbOCA)) the 1950s. In 1960, Wagner and colleagues reported 33 cases of the “rare” tumour mesothelioma in workers exposed to asbestos • Gas workers (in old vertical retort houses) in South Africa. • Laboratory and testing work (using chromogens) • Rodent controllers (formally using (alpha)-naphthylthiourea) In asbestos workers who have developed asbestosis the risk • Painters of lung cancer is increased at least five times. For chrysotile • Leather workers there is a linear relationship between exposure and risk of lung • Manufacture of patent fuel (such as coke) and firelighters cancer. Each additional fibre exposure (every ml a year) is • Tar and pitch workers (roofing and road maintenance) equivalent to a 1% increase in the standardised mortality ratio. • Aluminium refining Between 0.6% and 40% of lung cancers have been Asbestos related cancers attributed to occupation, depending on place and time. Chlormethylesters, used in ion exchange resins, increase the • Lung risk of lung cancer 20 times and have a short latent period of • Malignant mesothelioma—most commonly of pleura, 10-15 years. The type of cancer is small cell, also caused by uranium and beryllium (which also causes adenocarcinoma). occasionally peritoneal, and rarely of pericardium Painters have a 30-100% increase in lung cancer. This may be caused by heavy metal salts or chromates, organic solvents, or • Larynx exposure to silica and asbestos. • Possibly gastrointestinal tract Over 40% of people with asbestosis die of lung cancer, and Smoking and asbestos 10% die of mesothelioma. Mesotheliomas, which are predominantly of the pleura (ratio of 8:1 with peritoneum), Asbestos Tobacco Lung cancer rate have usually been growing for 10 to 12 years before becoming Ϫ Ϫ per 100 000 clinically evident. This latency can be very long—often 30 years ϩ Ϫ and sometimes up to 50 years. However, median survival from 11 the time of initial diagnosis is usually short—three to 12 Ϫ ϩ 58 months. ϩ ϩ 123 The amphibole fibres in crocidolite (blue asbestos) and 590 amosite (brown asbestos) carry the greatest risk of causing mesothelioma, but the serpentine fibres in chrysotile (white Smoking with concomitant exposure to asbestos greatly asbestos) can also do so, especially if they contain tremolite. In increases the risk of developing lung cancer: compared about 90% of patients with mesothelioma, close questioning with non-smokers not exposed to asbestos, a smoker will usually show some earlier exposure to asbestos. The exposed to asbestos has a 75-100 times greater risk if possible risk to neighbourhoods outside asbestos factories from exposure was sufficient to cause asbestosis, otherwise discharged asbestos dust or contaminated clothing brought the risk is about 30-50 times higher. This multiplicative home should not be forgotten. theory on effects of asbestos exposure and smoking, however, has recently been disputed The annual number of deaths from mesothelioma has increased rapidly from 153 in 1968 to 1595 in 1999. The latest projections suggest that male deaths from mesothelioma may peak in about 2011, at about 1700 deaths every year. Occupations with the highest risk of mesothelioma for men include metal plate workers (including shipyard workers), vehicle body builders (including rail vehicles), plumbers and gas fitters, carpenters, and electricians. Blue asbestos White asbestos 90

Occupational cancers Asbestos legislation Mesothelioma extending through needle biopsy tract Asbestos is controlled in the United Kingdom by three complementary sets of regulations: Occupations involving exposure to asbestos • Manufacture of asbestos products • The Asbestos (Licensing) Regulations (amended 1998) require • Thermal and fire insulation (lagging, delagging) • Construction and demolition work work with the most dangerous types of asbestos (coating, lagging, • Shipbuilding and repair (welders, metal plate workers) and asbestos insulating board) to be carried out only by • Building maintenance and repair contractors who have a licence issued by the Health and Safety • Manufacture of gas masks (in second world war) Executive • Plumbers and gasfitters • Vehicle body builders • The Control of Asbestos at Work Regulations (amended 1998) • Electricians, carpenters, and upholsterers • Armed forces (historical) lay down the practices that must be followed for all work with asbestos, including that which requires a licence. Employers must prevent the exposure of employees to asbestos or, where this is not reasonably practicable, reduce exposure to a level that is as low as possible • The Asbestos (Prohibitions) Regulations (amended 1999) prohibit the importation into the United Kingdom, and the supply and use within Great Britain, of amphibole asbestos— crocidolite (blue) asbestos and amosite (brown) asbestos—and, since 1999, of chrysotile (white) asbestos The supply and fitting of vehicle brake linings containing asbestos is prohibited in The Road Vehicles (Brake Linings Safety) Regulations 1999, and the European Union has amended the Marketing and Use Directive (76/769/EEC), which prohibits the marketing and use of chrysotile asbestos throughout the EU after 1 January 2005, with one derogation for diaphragms for the chlor-alkali process Forthcoming legislation will require employers to manage the risk from asbestos in non-domestic premises The latest amendments to the Control of Asbestos at Work Regulations 1987 (which came into force in 1999) target workers who come across asbestos accidentally, such as electricians, plumbers, other maintenance workers, and demolition workers. The Amendment Regulations also tighten the law on control of exposure to asbestos by lowering the action level and the control limit for chrysotile Tyndall beam photography showing asbestos fibres released by handling of asbestos boards (left), emphasising the need for proper protection when dealing with asbestos (right) Ultraviolet radiation Premalignant melanosis Ultraviolet radiation from exposure to sunlight causes both (lentigo maligna) in a man who melanotic and non-melanotic skin cancers (basal cell and retired after a lifetime of squamous cell carcinomas), but an excess of skin cancers in working outdoors outdoor workers is seen only in those with fair skin. Initial presentation may be that of solar keratoses or a premalignant state. Immunosuppression can increase the risk; other possible additive factors are trauma, heat, and chronic irritation or infection. 91